Memtest errors with good memory

Hello i just recently installed windows 7 right around when l4d2 came out, and since then my game has been running horribly though everything other then games is fine.. i just figured it was bugged up like many other peoples l4d2 game play, but after trying all t he odd ends to fix it i decided to use memtest to see if that would show me the problem.

Well after getting to test #3 it gets so many errors that it freezes memtest, so i thought ok problem solved ill RMA my ram and bam im good.. However while waiting for my RMA info from corsair i ran memtest on my other pc, memory is fine, so i put it in my pc and mine shows errors in every slot, so after trying to google to see what this could mean.. i have no idea, other then possibly all my dimm slots are fried/bad.

I've ran hard drive test, cpu benchmarking and memtest, though memtest has been the only thing to produce errors

My specs

Windows 7 ultimate
Gigabyte P35-ds3r w/ Intel Q4400 @ 2.4ghz
2Gb Dual Channell 1066 Corsair Dominator ram @ 5-5-5-15
2x 500gb SATA seagates
Geforce 8800gt



edit: The voltage is @2.1 and i've tried running at looser timings 6-6-6-18 with no luck