My computer will shut down without warning and without going through proper shutdown procedure almost as if it were a hardware issue

It sounds like you are experiencing an issue with your Dell OptiPlex 780 computer where it is shutting down unexpectedly. There are a few potential causes for this issue, and several potential solutions that you can try to resolve it.
Here are a few steps you can try:

1. Check for updates: Make sure that your computer is up to date with the latest Windows updates. Sometimes, these updates can fix issues with the operating system that may be causing your computer to shut down unexpectedly.
2. Check for hardware issues: Make sure that all of your computer's hardware is properly installed and functioning correctly. If you have recently installed any new hardware, it's possible that it could be causing the issue.
3. Check for malware: Run a malware scan to make sure that your computer is not infected with any malicious software. If you find any malware, remove it as it could be causing the shutdown issue.
4. Check for overheating: Make sure that your computer's internal temperature is not too high. If it is, it could be causing the shutdown issue. You can try cleaning the inside of your computer and making sure that the air vents are not blocked to help keep the temperature down.
5. Check the power supply: Make sure that your computer is receiving a stable power supply. If it's not, it could be causing the shutdown issue.

If none of these steps help to resolve the issue, you may want to try contacting Dell for further assistance. They may be able to help you diagnose and fix the problem.

hi there.
Laptop performance slowing down, or the laptop isshutting off completely because the laptop is trying to protect itself from damage caused by an excessive heat build-up. ... There are times when a laptop will turn offbecause of a virus or malware, hardware or software problems/conflicts as well.2 Nov 2013

Don't panic!... Is your "laptop shutting off by itself" or "slowing down ...

https://www.youtube.com/watch?v=74agkgZdzkI
What is the problem if laptop shuts down automatically?If removing air doesn't fix shutdown issue, it is a faulty hardware (can be anything), related to overheating or serious power related failure, such as bad battery or adapter. Overheat issue will result in unit turning on, but shuts down after about the same time (i.e. 15 sec).29 Jun 2015My Laptop automatic shutdown in few seconds - Laptops - Laptop ...
What would cause a computer to keep shutting down?An overheating power supply, due to a malfunctioning fan, can cause a computer toshut off unexpectedly. Continuing to use the faulty power supply can result in damage to the computer and should be replaced immediately. ... Software utilities such as SpeedFan can also be used to help monitor fans in your computer.5 May 2017Computer turns off without warning - Computer Hope
How do I get my computer to stop shutting down?Cancel System Shutdown or Restart. You cannot cancel a restart or shutdown using the Shutdown Event Tracker Windows interface. It is only possible to perform this task from the command line. To cancel or abort system shutdown or restart, open Command Prompt, type shutdown /a within the time-out period and hit Enter.1 Apr 2013Stop, Cancel, Prevent, Abort System Shutdown in Windows 10/8/7www.thewindowsclub.com/abort-system-shutdown-windowsSearch for: How do I get my computer to stop shutting down?
or go to this link to find out more.
Laptop keeps shutting off after few minutes

Is it only shutting down when unattended ? Which operating sytem ?

if your laptop keeps shutting off

If your laptop suddenly shuts itself off for no apparent reason, there are several factors that can contribute to the problem.

When you troubleshoot the laptop, remember that it is also possible for a combination of causes to be at work.

Excessive Heat

Keep Cool

All newer laptops have built-in heat sensors that shut the computer off when it exceeds a pre-set temperature threshold. Install and run a temperature monitoring utility to determine whether the laptop is overheating.

might be getting hot

check you CPU make sure its securely seated and has thermal grease

http://www.hardwaresecrets.com/article/Thermal-Compound-Roundup-February-2012/1490

Hardware Issues

If you replaced or installed new hardware in your laptop, use the device management utility to review if there are any resource conflict or failure reports. You can also remove unnecessary hardware and run the laptop to see if the problem persists. If it doesn't, reinstall each hardware component and re-test until the laptop fails.

Operating System Issues

The operating system start-up controls can affect how the laptop performs.

Follow the operating system developer's instructions for entering the start-up program, and confirm that the settings are what your laptop requires.

Power Supply

If the laptop computer suddenly shuts down, it could be because of a break in the power supply.

If the laptop is plugged into an outlet for power, check to see if the plug was pulled from the socket and make sure the cord is properly connected to the computer.

If the laptop is running on battery power, then it is possible that the battery is drained and no longer has enough power to run the computer.

A simple recharge of the laptop battery should fix the problem.

Typically, a laptop has an indicator on the screen that tells how much battery life is left so that a shutdown is not a surprise.

Failing batteries can produce unexpected laptop shutdowns.

Use a battery monitoring utility to determine whether or not the battery is healthy and replace it if it isn't.

Malware

Unfortunately, rootkits and viruses can cause your laptop to shut down without warning.

You will probably have to take the hard drive out of the laptop to be able to scan it fully and remove any malware that is installed, or the laptop will shut down before the scan and repair can finish.

http://www.malwarebytes.org/mbam.php

Malwarebytes is as the name says, a Malware Remover!

Download the Free Version from the link above.

Download, install, update and scan once a fortnight.

http://www.spybot.info/en/index.html

Spybot Search & Destroy 1.6.2 is a very good, FREE Anti-Spyware Program.

Download, install and update it.

Then SCAN with it.

Update it, and scan your System once a fortnight.

Hope this helps

Hello Pattiaknight,Make a desktop shortcut to shutdown and include a switch that forces all open apps to shut down without warning.

Just right click the desktop, New, Shortcut, type:

Shutdown -f

Shutdown -f closes any open programs without warning.

Now instead of shutting down the usual way, just use that shortcut to shutdown. If the error stops it means some program wasnt shutting down properly on occasion.

Please let me know if you any further questions or concerns.Also please rate it if you like the answer,it helps alot.
Thanks.

make sure it is not overheating and that your ram and processor have a good connection.

There are several reasons that can cause old Windows operating systems to shut down. Has this always been an issue or did it just start happening? If it just started, then think back to what you may have changed on the system...hardware or software. Remove software or hardware and try it again.

You can also try disabling the fast shut down sequence by following these steps:
1. Go into msconfig (this can be done by typing msconfig under the command prompt)
2. Go into advanced.
3. Put a check mark in the disable fast shutdown box.
4. Click ok and ok again.
Try shutting it down.

If that doesn't do the trick or its already disabled then check out this link:

http://support.microsoft.com/kb/202633/en-us

I hope that helps. Check back and let me know! Thanks.

Software issue or error
Errors generated by software programs can cause a computer to reboot unexpectedly or without warning. If you are running Windows XP see the below section "For Windows XP users" before continuing. If you are not running Windows XP or following the below steps still cause your computer to reboot without warning. Boot your computer into Safe Mode, and let the computer run in Safe Mode.

If the computer is still rebooting in Safe Mode the issue is likely not software related but something else, skip to the next section. If the computer is not rebooting in Safe Mode it is likely you have software related issue. We would recommend you run through the basic troubleshooting section for your operating system.
For Windows XP users
Windows XP is designed to automatically reboot each time an error occurs such as a BSoD. Although this may be nice for errors that do not occur often, users who have a re-occurring error may wish to identify the error to troubleshoot it. Below are the steps on how this feature can be disabled and enabled in Windows XP.
From the desktop right-click on My Computer.
Click the Properties option.
In the System Properties window click the Advanced tab.
In Advanced click the Settings button under Startup and Recovery.
In the Startup and Recovery window uncheck the Automatically restart check box.
Click Ok.
Now if the computer generates and error it should not automatically restart and enable you to display any errors your computer may be experiencing.
Hardware issue or error
Any failing hardware component in your computer could cause your computer to unexpectedly generate an error and/or reboot without warning. If you have recently attempted to add a new hardware device, remove that device to make sure it is not causing your issues.
Make sure you are not encountering any hardware conflicts by viewing Device Manager for errors.

New drivers can also cause this issue, if you have recently performed any hardware driver updates you may wish to try an earlier version of the drivers.

If you have updated drivers and removed any hardware that could be causing this issue and continue to experience random reboots, it's possible that the memory is bad in the computer.

Finally, hardware devices that are not installed properly in the computer can also cause random reboots. Make sure all the cables and expansion cards are connected properly to the computer. The best way to determine this is to disconnect and reconnect all cables and expansion cards.
Computer virus
Computer viruses such as the blaster virus are written to reboot your computer without warning. Usually these viruses will make the computer reboot ever 5, 10, 15 or 30 minutes after the computer has booted.
If you believe your computer may be infected with a virus or are uncertain if your computer is infected with a virus make sure your virus scanner definitions are up to date.

Heat related issue
Many computer today are designed to turn off or automatically reboot if the computer, processor, or other device in your computer gets to hot. If you have heard any abnormal noises coming from your computer recently such as a high squealing this could indicate a fan may be failing in your computer.
You can first start by verifying the fan on the power supply is working by examining the back of the computer and seeing if the fan is moving and moving smoothly. For all other fans in the computer you will need to either open the computer and make sure the fan are working (processor fan and case fan) and/or if your BIOS monitors the RPM of the fans enter BIOS and make sure the BIOS does not report any errors.
Users may also be able to determine how hot their computer is by onboard thermal sensors, if your computer comes equipped with these sensors make sure your CPU is not running to hot.
Issue with operating system
If after following each of the above recommendations your computer still continues to reboot it is likely that you are experiencing a Microsoft Windows operating system related issue that cannot be explained. To help make sure this is the case please try the below steps.
Reboot the computer and enter CMOS setup as the computer is booting.
After you have loaded the computer in CMOS setup let the computer sit.
If the computer does not reboot while letting the computer sit in CMOS it is likely that you are in fact experiencing an issue with Microsoft Windows and it is recommend that if you have followed all of the above recommendations that you reinstall your version of Microsoft Windows.

That is a strange problem.
I will help you to create a shortcut on your desktop for that icon, whenever you need to shutdown your computer, just click that shortcut on the icon.

Right click on the Desktop.
Left click on New > Shortcut.

In the Type the location of the item: textbox enter
%windir%\System32\shutdown.exe -s

The -s parameter is used to shut down the computer.

The following two parameters can be used with -s:
-f Forces running applications to close without warning.
-t xx Set timeout for shutdown to xx seconds.

The following command would shut down instantly.
%windir%\System32\shutdown.exe -s -f -t 00

Click the Next > button.


In the Type a name for this shortcut: textbox enter
Shutdown My Computer (or some other name of your choice)

Click the Finish button.


Whenever you want to shutdown your computer, click the shortcut on your desktop that says ShutDown My Computer, and your comptuer will shut down the usual way, the way it used to shutdown.


Actaviosan

DaveBaker,

Here are a couple of tips that I've collected that may address your problem.


Go to start>run>then type in "cmd" without the quotes. this will bring up the command prompt. next type in the following command: "shutdown -s" without the quotes again. This should tell your system to shutdown your computer entirely.

Next
Try doing this. Hold down "ctrl" and left click "shutdown". This skips some windows XP shutdown procedure and should do the trick.

And, finally

http://support.microsoft.com/?kbid=831431
You cannot log off, restart, or shut down your Windows XP-based computer This article talks about an issue with Norton 2003 incompatibility.


Would appreciate any feedback as to which of these worked for you.
Thanks much!
Ron-