I recently had the same problem w/ my MD-MT15 last week. I unplugged the unit from the power source for a few minutes, then I just kept trying to insert the disc over and over. Finally after about 20 tries it worked and the playback was not harmed at all. I havent tried the disc agian, but I dont think it was a random error since the other discs from the same recording worked fine. Hope this helps.