Seems that it's a hardware error of some sort, with RAM being the most likely suspect, IMO.
I would run Memtest according to instructions, after downloading the .iso file and burning it to CD using an iso-burning program.
The iso-burn program that I use is Active@ ISO Burner - http://www.ntfs.com/iso_burner_free.htm
, but there are many other programs which can be used to transform the .iso file into a bootable CD.
MemTest Manual - http://hcidesign.com/memtest/manual.html
Memtest86.com - Memory Diagnostic - http://www.memtest86.com/
Please follow the instructions for using this diagnostic tool, if you should decide to run it.