PC restart suddenly without infected by any malware

[CuteSniper22]

My PC screen goes blank and suddenly restart.... I don know what happen

The following is programs I run before this problem occured...
1. Avant Browser 11(status: online)
2. Windows Media player 10

MY PC Info
1. Intel Processor 4 2.66ghz
2. Windows XP SP2 5.1 build 2600
3. 256 RD-RAM
4. 40GB Ultra ATA hard disk drive(C drive and D Drive NTFS)
5. ATI Radeon 9700 128RAM (400Mhz)
6. Default System Bios (Dell Dimension 8250)
7. Sound Blaster Live!

Note: I can confirm that my pc is not infected by malware because I do scan my pc multiple times with various type of anti virus product and online scan.

 

[Archangel]

did it ever happened before? how old is the pc, and when did it start?

and especially,.. have you checked the CPU temperatures? ( maybe have a look inside the case to see if there is a lot of dust/dirt in the heatsink of the CPU cooler, you might want to clear it if so. ( because if its a system that ran good for quite some time, and suddenly starts restarting, my first guess would be overheating )

 

[CuteSniper22]

thanks ... but i think i should tell situation happened more clearly to u...
MY pc haven't overclock yet (still in default speed)... I think it won't overheat...

When It happened...
1. no any error messege jumped out ...
2. the screen suddenly goes blank.. then restart
3. Even... I didn't run any program or in screen saver mode, it still restart randomly...

 

[_simon_]

Sounds like your power supply unit (PSU) is failing.

If it is the PSU then you'll probably find the restarts get more frequent and at some point it won't restart at all, it will stay off.