My computer, a Dell Inspiron 570 Desktop, has done this twice in the last few weeks: I have been working on a file and without warning the computer exits the program and goes through its elaborate restart procedure. The first time, I blamed myself for switching the computer off improperly, but that wasn’t the case the second time.
Was it the same file both times?
Often times, random resets can be blamed on overheating. A quick and dirty way to check that is to open the case and pointing a regular (house) fan into it and see if it resets again. But just checking to make sure the CPU fan and heat sink aren’t full of dust would be a good start.
I don’t have the courage (or the expertise) to open the case. Yes, it is the same file…I do have a small electric fan I could point into the vent on the back; but I’ve had enough troubles with this thing lately and I don’t like to take chances. We have also been invaded by ants lately, and I suppose it’s possible they could get in there.
Had a spider cause a metric ton of trouble in a computer once… Just sayin…
Don’t bother with the small fan, if it’s not over heating, it’s not going to help and if it is, that’s not going to make a difference.
What kind of a file are you working it? Since it was the same file, I’m going to guess either it or the program you’re using is corrupt. So my suggestions are going to be (without knowing the file type) something along the lines of (if possible) copying the data to a new file or working on the file, at least temporarily, with a different program. But these may be easier said than done.
Also, if you’re not interested in opening the case, that’s fine, but at least glance at the back and front (usually hidden on the front) and make sure all the little holes are clear of dust. If they’re not, use a vacuum with a hose attachment and carefully suck the dust out. Don’t use compressed air to blow it in.
Unless you use that file a lot, it doesn’t sound like over heating is the issue, but once you start having these kind of issues, it’s not a bad time to check this out as well.
On top of which, pointing a fan into the vent on the back is counterproductive: that’s the vent the computer’s internal fan is trying to push hot air out of.
If the OS had a chance to record the cause of the crash and write a crash dump, you could get a good clue as to what is going on by checking the system event log for any crash event recorded just before the startup events. A more elaborate analysis is possible with tools like WinDbg which process the crash dump, but that’s much more complex and not usually necessary, since there will usually be an event log entry with the root cause information. Sometimes you need to Google the event description and parameters to see what they mean.
For example, I’ve had two such recurring restart events in recent years and the system log helped trace it both times. Once it was traced to a DLL associated with a recent system change. In the second case, the system failed to record a cause the first time but managed it the second time it happened. It was a pagefile read failure, and I eventually traced it to the fact that I had a secondary page file on a drive that was starting to go bad and getting lots of read errors.
If it’s genuinely restarting, then there’s probably an entry in the event log indicating why. Check in the Event Viewer, probably under Windows -> System.
I had a dust problem once, and the computer shut down, and didn’t restart.
Are you getting a blue screen of death? Which program, and I also ask if it was the same file.
If it was a BSOD, see if you can write down the information and Google it. Almost certainly someone else has had the same problem.
ETA: Not that checking your fan vents and sucking dust out isn’t a good idea also.
No, no blue screen.
BSOD??
I had a Dell computer that used to randomly restart some years ago. I finally figured out it was the mouse – it must have had a short in it or something.
I was thinking I had to replace the computer when one day I just lifted the mouse off the table and it restarted. Then it struck me. I replaced the mouse and the computer got better.
Assuming you’re using Windows 7:
In Control Panel, go to System.
On the far left there will be Advanced System Settings. Click into this option.
The third tab will be Advanced.
At the bottom of this tab you will find a “Settings” button in the Startup and Recovery section.
Go into this and unselect “automatically restart” under system failure.
Now if you are suffering a Blue Screen of Death (BSOD) you will see it. Find the stop code and post it here.
BSOD = Blue Screen of Death.
Are you sure it wasn’t just the automatic reboot after Windows had installed updates? What days of the week were these restarts?
You can read the machine’s temperatures yourself. Try Speedfan, or CPU-Z and GPU-Z, as free apps, if you don’t have such an app already.
I don’t know if there is a connection, but every time I shut the computer off, it “installs” 10 “updates” that I don’t understand. The next time I start it up, it begins to “configure” the updates; at the 30% point the screen message reads that the configuration has failed and the changes are “reverted.” This is beyond my comprehension.
You still haven’t told us what, if anything, you found in the event log which I suggested you look at – and which another poster immediately following then also suggested you look at. Which just confirms the theory, advanced by someone else in another thread, that many posts here seem to be write-only. 
You probably need to find a local computer repair shop, then.
Same for me, relatively new Dell, randomly shuts down and reboots, doesn’t matter what kind of file I’m working on, mouse or no mouse, giant PITA, never getting a Dell again. Plus Windows 8 pretty much has ensured that my next device will come from Apple.
I did take your advice about the Advanced System Settings. The Log bit wasn’t so simple: I had no guide for that and I wound up looking at a page of my Document Library.
It sounds like you have a Windows Update that is failing and causing the whole series of them to fail. Perhaps your computer is trying to install a big one like Service Pack 2. Go into Windows Update under Control Panel and check View Update History. This will show you all the updates sorted by date. However, you can also sort them by status, which will tell you which ones are failing. Please let us know which ones are coming up in here if any.