Is this a new build? What is the model of CPU, DRAM, and motherboard?
Try running Memtest86+ at the first boot after it has sat for a few hours. http://www.memtest.org
2 yrs old,
P4 3000Mhz, 2MB L2, 800 Mhz FSB
Transcend 2GB and
Gigabyte (no surprise here!)
Will try memtest.