I just purchased a Mac Mini Core Duo 1.66GHz with a combo drive for my parents, and I'm having the strangest problem. Before I sent it to them, I didn't actually try to read any burnt DVDs (neither + or -), just CDs, CD-Rs and factory DVDs. DVD+/-R are the only discs that seem to be causing me problems. I put the disc in the drive, and it just spits it back out. I've tried a few different brands. I burnt the DVDs on my MBP, and they play no problem in every other machine I've tried them in. Any ideas?