LiteOn HD-A760GX recordings freezing on playback ?

My Lite On HD-A760GX is 18 months old and recent recordings freeze on playback partway through. Sometimes they start up again and then do it again. Other times I have to start again. Is this a bad sector on the disk and could it be solved with a reformat? I have not updated the software since I bought it. The problem with this is the dvd has stopped recognising disks (so I can't copy anything off). Can anyone recommend a replacement PC drive?