DVDR &) malfunction (Philips DVDR70 DVD Recorder)

[qanda]This thread is about the Philips DVDR70 DVD Recorder. Click here to see full specs[/qanda]Hi My philips dvdr 70 will often refuse to play new pre-recorded dvd`s but it will always play ones which I record on it. IT STARTED TO PLAY A FILM WHICH FROZE ABOUT 2 THIRDS THRO BUT THEN REFUSED TO RECOCNISE THE DVD AT ALL, I have bought and used a philips cleaning disc but no change . any Ideas ? thanks in advance John