For me it was the burning speed, I had the same 324 on most games and I got it fixed by burning at 4x, I burned around 30DVD-R's at 2x(odly enough Sonic Unleashed worked on my first 2x burn) and VERY few worked, I burned it at 4x and none gave me problems, also could be your DVD burner, I have one on the living room computer and its much better than the one I used, memorex @ 16x speed I get 98% on all my burns so far on DVD info pro, the one I used to do the last 30 burns came with an E machines and highest speed was 4x, needless to say it sucked and I'm glad I didn't buy those expensive verbatim DVD-R's