This problem pertains to a rig I put together 3 months ago and there has been no problems until recently. I started getting errors in windows and in different applications about missing windows files and whatnot. Restarted computer and then I started to get blue screens right after windows loaded and could not boot into the OS (but I could still boot into safe mode). Ran memtestx86 and it was failing test so I removed one stick of ram (i have 2x1gb) and problem gone, boot into windows fine, no more blue screens. So then I proceeded to put back the stick of ram back in and windows booted up fine (and therefore I thought maybe perhaps the stick of ram was loose). Ran Orthos, everything was fine, stable for 7 hours (specs are in sig). Left my computer idle and came back later in the day to find another blue screen. Restarted computer, booted into winxp fine, and ran orthos and was unstable after 3 seconds of testing. Then I tested each ram stick with memtestx86 and orthos and ran fine, put both sticks back in, ran orthos fine again, but AGAIN later in the day came back, computer blue screened and orthos is no longer stable. Can anyone identify or know what could be causing this, perhaps faulty motherboard? Thanks for your time.