Basically the TOC thing... you need to have a disc with a bigger Table Of Contents than the one you're swapping to. So DVD9 games = bigger games = bigger TOCs. I agree with Cinder- this is more likely what's behind your skipping issue. Rebuilding in my opinion does nothing but here's how anyway. 1) Open ISO Buster, get your disc / ISO up, right-click the ISO tag and go; Folder tree and file information > List tree-info (in txt file) > LBA, Relative Path Save your text file to a new folder. Then select all the files in the ISO, right-click and go Extract Objects and select the same folder. 2) Open CDGENPS2, go; Advanced > Import Tree File Then go File > Save Image. There you now have a rebuilt ISO. You can burn it with Nero or whatever you like though. I don't believe it will make a difference, but hey give it a shot.