Help w\Memtest86 3.0

Hi all, i've got a problem and not sure what to do. I have 3 separate sticks of memory, and none of them will pass memtest86 3.0, or memtest86+ 1.0. What to do next? It all started when i wasnt able to OC hardly at all. I mean 174fsb was it! My older rig could do 10x200 w- no problems at all. Which is why i tried the older stick of micron pc2100 from my old rig. When it failed i knew something wasnt right. I've tried different floppys, and 3 different downloads, to no avail. And to make things worse, its random errors, nothing consistent at all. Tried ten million different timings on each stick also. Below are my old and new sys specs. Thanks

OLD: xp1700 TB rev.b
NF7-S rev 1.1
micron pc2100 512
maxtor 40gig 7200
enermax 365

NEW: xp2500 Barton
NF7-S rev1.1 (same as old)
kingston value pc3200 512, AND geil value pc3200 512
wd 40gig 8mb 7200
enermax 365 (same as old)

 

have you tried them in a different slot

 

Yes, all three slots.

 

do you get errors whilst in windows or have you tried any other ram testing software such as
http://www.simmtester.com/PAGE/products/doc/docinfo.asp