Alright, I'm working on my friends laptop and I have ran into multiple issues. Their laptop is a toshiba im not sure of the kind right now.

But I've had a few suspicions of my own to why this is happening

1.) maybe the battery has a dead cell. So I had them remove the battery and plug the AC power into the laptop. It worked.

2.) next im thinking it is overheating. when a laptop overheats, it will automatically shut down. so i gave them my cooling pad. i just gave it to them yesterday so we'll see if it works or not.

3.) it could be bad memory causing a system reboot.

4.) finally, it could also be a bad sector in the hard drive. This may also cause a system reboot.

The last too will cost money. Im hoping that these last two are not the situation and im hoping it will be the second one. So if anyone has had this problem before and have fixed, please let me know.

You seem to be going the right way about diagnosing the problem, obviously lots of people will have experienced problems with lots of other makes of laptops rebooting themselves. It is very likely that it could be the laptop battery if it works fine on AC power and I would definitely give the overheating possibility a try.

Testing the RAM needn't cost anything, follow the advice from Bill below to test your RAM.

Originally Posted by Digerati

You might want to test your RAM too. You can test your RAM using one of the following programs. Both require you to create and boot to a bootable floppy disk or CD to run the diagnostics. Using the floppy method is generally easier and yet another reason I still include floppy drives in all my new PC builds. However, the CD method is just as effective at detecting RAM problems. Allow the diagnostics to run for several passes or even overnight. You should have no reported errors.
[indent]Windows Memory Diagnostic - see the easy to follow instructions under Quick Start Information.
or
MemTest86+ (for more advanced users) - an excellent how-to guide is available here.

well i tried digerati's methods and i didnt get it to work, well the first one at least. I have had any time to try the last one. but thanks anyways ill keep you updated

ok so it worked. thanks to anyone who worked

What was the problem?

sorry about the long absence anyways it worked for a while, but now its not working again. I still think its over heating but obviously thats not the issue. we've tried multiple solutions none have worked im at a loss here lol. ok so just to run over the things i have tried.

Install a cooling pad
installed more ram
check background applications
ran a virus scan
updated drives

lol what else could it be??

ughh i hate computers sometimes even though i love them yes i know im confusing so anyone who can help please push me in the right direction thank you very much

You say installed more RAM. There still could be faulty RAM causing the system problems. I recommend you give the memory test a try.

Does the laptop work fine on AC Power? Or does it still reboot?

And,

installed more ram

Are you sure the RAM is compatable with that machine?

yea i mean it works fine except for the fact that it shuts down

andit still reboots on ac power

I had a PC that did this. The memory timing was the problem. The performance and stability of any system depends in part on the memory being used and the settings for the RAM timing. Check your timing to see if it is set right.