I tried two different discs - both taken from their original packaging. I use DVD-R - got that one sorted out a while ago.

Comedy of errors - went to use the pc last night and the monitor has just about died - it just flashes on and off and wouldn't turn off. I'm using the laptop right now. Once I get a new monitor set up I'll try importing the programme Amos suggests. Otherwise, looks like I may need to buy a new DVD drive!