I have looked at it and they are able to write to CD but not read them. If you insert a CDR with files on the PC asks if you want to open a writable folder, but open it and nothing is there. Put the CD into a different drive and there the files are.
I have tried replacing the drive but the problem is the same, so I imagine it's a driver problem.
I have tried rolling back the PC and the drive then works, but he has installed loads of programs and made other changes which are not there when the it does.
I realise that I could do a repair installation but is there a quicker way (replacing a dll or something).