Could be a bad connection but sounds more like hard drive has bad sectors, easyiest way to find out is if you can get hold of a hard drive you know is working swop it out and see if it loads on that.
Q6600-P5K Premium+Alphacool w/blocks
EVGA 8800gt+Koolance w/block
Samsung f1 raid0 +f2 hard drives
Enermax infinity 650w Popeye67's Blog