I'd be thinking along the lines of the discs you are using...
Does your dvd burner support + or - or both...
It can also come down to the brand of disc, some players just wont play certain brands...
Also if there has been something put on a dvd R disc, it wont burn over that again even if there doesn't seem to be anything on it, once used they cannot be used again...
Imation is a reliable brand...
