hi, i'm not new to macs but i figured someone here would able to send me on the right path. i'm having this wierd problem, i tried burning cd's at 1X, 4X and Best speed and i tried buring DVD DL at 2X and Best speed with toast 10 on an alluminum iMac 20" running osx 10.5.7 without success. the wierd part is that i can burn standard dvd's at any speed and it works but the other two NO LUCK. i get this wierd message after a few seconds into burning. here it is ASIS The drive reported an error: Sense Key = MEDIUM ERROR Sense Code = 0x0C WRITE ERROR i press ok and then i get another message and it says: The drive reported an error: Sense Key = MEDIUM ERROR Sense Code = 0x73, 0x03 i press ok and then i get a last message telling me: "The disc failed to be written." i press ok one last time and the disc pops out. i tried burning an audio cd with iTunes and i get a similar message. what i have realized after a few tries is that the discs are never burned, they stay blank. Any one have a clue on what i should do before sending it for analysis in an apple store???