maybe download Hirens Boot CD.
and use some of the various testing utility's on the cd?

http://9down.com/Hiren-s-BootCD-9-0-...rd-Patch-9670/

Direct download link
http://files.9down.com:8080/HBCD9.0_www.9down.com.rar

also google for memtest, and give your ram a few run's with that app also.