Pc suddenly shuts down

If the temp achieve to 99 to 100 oC, then your notebook would automatically shutdown. This because the BIOS is already program to force shutdown if the the temp is getting to 100 oC. (or sometime 105 oC) to prevent a absolute damage to your laptop.

My computer remains on for 6 to 7 hours at once at a time, and this never has occurred. Maybe the fans need a little bit of cleaning? My computer is two years old and is used heavily!

Take a read here: http://www.almico.com/sfdownload.php It is a virtual monitor of your computer's heat. You could by a heat sink, but your best best is to see if cooling is actually the issue.

My brother had this issue, but the opposite. His computer would turn on in the middle of the night.

I said I don't think it's overheated. When it shuts down, it's not hot at all (just a bit warm, which is normal).
The fan works, and the air isn't very hot.

I downloaded the program and the temperatures are:
HD0: 36C
core0: 46C
Core1: 52C
Could they be causing the problem?

I don't think my pc is damaged. So, I suspect virus softwares.

You'll need to run it for >4 hours to get accurate results, because it takes averages. How long does the computer have to be on before this happens?

My very first laptop would do this because of a virus. Could your computer be affected?

I don't know. It happened 3 times the last 2 days.

I download lots of files, and, although I try to be careful, I might have downloaded some viruses

If you're using windows, see what's in your task manager by clicking alt-ctrl-del. See if there are any strange processes. If it's not the heat, could it also be the battery? In addition, check your RAM and memory, and see if it is full.

Check your laptop's power option. To do this go to: Start menu Control panel Performance and maintenance Power options

There you can see tabs having options like Turn off hard disk ; turn-off monitor etc...

Check power options carefully.

No suspicious processes. Physical memory is at 64% Isn't that a bit high? But I don't think that if you run out of memory the pc shuts down...
Hard disk has still lots of space.

I have windows 7 and can't see these options.

They must be outdated instructions. However, the options should be in control panel. On my IBM, there is software designed and installed already that deals with power savings, etc. See if that exists.

It happened today too

I checked the settings, there was nothing abnormal... In addition, i haven't changed these settings for months.

Post Merge: 11 years ago

I uninstalled all recently installed programs. Lets hope

My conclusion is a virus or a program you've installed in the past few days.

Also, if you're good with computers, check the Bios.

I think it was temperature, because I had a program that was checking the temp. running while I was playing a game, and the core temp. had reached very close to 90, and the pc shut down again during this test.

Then, I did the followings:
1) Removed the battery (used only the charger to provide the laptop power)
2) Made sure that there is plenty of air for the fan
3) Reduced the processor's max state to 70%

After these, the temperature wouldn't go above 70C during game, and the pc wouldn't shut down