These are just some of the artifacts I’ve seen.  I also have seen a split second of corruption like other people have posted.  Here’s on similar to what I’ve seen also.

http://forums.macrumors.com/attachment.php?attachmentid=300905&d=1314678276

I’ve run Handbreak for well over an hour, ran 2 full passes of memtest with no issues found.  So the processor and RAM should be fine.

I’ve upgraded my RAM, Crucial 8GB’s, and WD Black 750GB 7,200rpm hard drive.

Here’s a good forum discussing this issue. 

http://forums.macrumors.com/showthread.php?t=1196552