Since i posted the thread as above i have done some more burning with better results.
I managed to buy a 16 pack of dvd-r and dvd+r of different makes of media and burnt them without doing any other tasks on the pute and they worked fine. dont know if it was the media or me doing other stuff while it was ripping the film then burning? I have burnt numerous stuff on cd, films, games , data while doing other tasks and hardly any coasters. Did'nt realise how twitchy it might be with dvd's. just thought id share that with u all.