Bad RAM perhaps? Run mem-test or somthing similiar to disqualify that option, and then just beginning testing one part at a time until you find the culprit.

You could also try firing up Dr. Watson under Windows and see if any errors are logged. If you're using 2000 or XP check the system log files for errors that my be associated with your problem.

If all else fails, it sounds like a great excuse to buy a new laptop. :D

Dr. Watson says that the last error was BG2 in february.

Where do you do mem-test? And I don't think that my parents would be happy about getting me a new laptop. Considering it took me a few years to be able to convince them to get this one.

Sleep mode, hardware standby mode, hibernation, whatever you want to call it, is not necessarily the same on a laptop as it is on a desktop machine.

On a laptop the screen, laptop, hard drive, power etc. all shut down completely. The method used to restore the machine from this state varies from machine to machine. On some you just press the power button, on others you have to hold down a particular key at the same time to prevent it performing a "cold" boot instead.

I doubt it is the power supply or its cable, as the battery should take over if that were the case. You could test that is actually happening by cutting the power supply off at the mains (rather than by unplugging it at the laptop end).

I had a problem with my power cable at one point, and that was fairly easy to diagnose because the battery was draining (and the charge LED stayed off).

My machine is several years old though. You shouldn't really be experiencing problems in that area unless you flex the cable a great deal (many times a day).

I understand the differences between laptop standby and PC standby however the problem was that it happened instantenously without my input, so I don't think it was standby.

try to scan for viruses. update it first.

It's the fact that you weren't providing any input both times that makes me suspect the machine's own (not Windoze) power settings.

When I first got my laptop (which was used), it was set so that during periods of inactivity the screen would go off/blank after 3 mins, the hard drive after 5 mins, and after 7 mins the main power would go off.

Fairly obviously, if the screen is already off, there's no way to see a query box even if one is displayed. It's also possible to set all 3 options to the same time delays, so that it will power down almost instantly.

The settings for mains and battery power can usually be set independantly.

It might be worth searching for a "burn in" test utility, and running that whilst on mains power and avoiding the use of the mouse and keyboard. You'd be testing several things at once that way.

You might also want to check the Toshiba site to see if anyone else has had similar problems with that particular model.

I had an issue like that one where my laptop had a Wake on LAN feature for the Network card. For some reason the laptiop switched off at random times when connected to the interenet. When I turned the Wake on LAN off (in the BIOS) this never happened again.

Hope it helps.

to answer your update question, it could possibly be the power cord, if running it on battery fixed it, it is probably a faulty conection in the cord..any chance it happens when you move the laptop? as mine does that, since some body set on it in the car :/ if that is the problem, it can be fixed by getting a new cord

experiment more with battery power... if it happens regularly on cord but never on battery you have a winner. If the system is running hot it could be you have a voltae regulation problem... try borrowing a power adapter from someone who has the same laptop model if you can

@Baron Night: I've never heard of viruses which can switch off computers just like that. Shutting down maybe, but not switching off like when pressing the power button.

@Wisardry: Thanks for the suggestios. The problem is that it wasn't a period of inactivity when these happened. Running media player and music doesn't count as inactivity. neither does disc cleanup. I'll check the other stuff you suggested.

@T-D-C: I wasn't connected to the net when the problems happened.

@Stormy and Thoran: I'll try that too.

Thanks everyone for your help so far. I hope I can find out what was causing this problem.