My computer restarts

[Stile]

Few days ago when I code DV to MPEG-2 (12 hours of coding), my computer restarts sometimes after an hour, sometimes after 11 hours of coding. I frameserving from Premiere 6.5 to TMPGEnc 2.53. I am using WinXP Home Edition with SP1. I have Athlon 2000+, 256 DDR RAM, Seagate Baracuda 80 GB and 40 GB at 7200 rpm. Temperature of procesor is 68C when I'm coding. I tried to repair Windows with Norton Utilities and it didn't help.
Does somebody know what is the problem?
Thanks...
P.S. The problem occurs few days ago. Everything worked fine and I coded a lot of material.

[hardwork12]

Few things:

68 deg C for yor CPU is too hot for my liking. May want to look into a better heat sink fan (or more case fans) looks like the one you may have is not rated for a Athlon 2000+. That being said generally if your CPU gets too hot it halts but it may cause a processing error (generate a BSOD) and the system reboots on ERROR.

The most likely cause is the memory so I would test this first. Go to:

http://www.memtest86.com/

Download Memtest86 3.0 release. Run this and it will install to a floppy disk and make it bootable. On restart the floppy will boot and start the test of your memory. This test tests all memory. If it fails the problem can be the CPU's L1 or L2 cache or the memory stick(generally 90% of the time the failure is the memory stick). If the test passes after running overnight the memory is OK.

One thing to keep in mind is that this test is NOT CPU intensive so if the problem is that the CPU is getting to hot causing a problem for the L1 or L2 cache this test will not pick that up.

A good CPU intensive test used routinely to test the stability of systems is PRIME95. Go here and follow the directions:

http://www.mersenne.org/freesoft.htm

If memtest86 passes an overnight run but Prime95 fails after some period of time I would suspect the high CPU temperature and improve the cooling (can try runing with the case open and see if this drops the temperature of the CPU and see if prime95 now runs overnight without failure).

[mpojeep]

Stile,
My 2 cents worth.....
You might also want to take a look at your power supply. Make sure it's AMD approved and I would not go below 400W as a minimum limit.
Also, make sure you have a lot of air movement to keep all those puppies cool!---I would recommend installing at least 2 case fans.