Hello all, It seems like my iMac will only read some DVDs. It will not read any commerical movie DVD (tried Indiana Jones, Wall-E, Finding Nemo), but for some reason will read my girlfriend's exercise DVD, blank DVD-Rs and DVD-R's I've created. For the DVDs that it will not read, it sounds as though it is trying, then after 30 seconds or so, it spits it out. Anyone know what is going on here? How can it read certain DVDs, but not my movies? Any help will be appreciated! Thanks.