Install motherboard monitor and check if your vault lines are correct. Like has been said remove 1 of the ram modules and swap and do the same with the other. Remove everything except the basics to boot. Try a spare GC. Try setting your bios to defaults. What make of drive is it? If it's maxtor it's probably dying a slow death. Each drive manufacturer usually has a util to check the disk for bad sectors. Download AVG free and keep it updated on your pc.