Jim I deeply suspect that one of two things are the case. 1 your dvd drive is read only i.e. not a writer but I don't think this is likely you sound like someone who knows what they are saying.
Two is that the dvd drive is fritzed. this has happened to me in the past and i have had to replace it, they cost about £30 up. Try to clean it with a cleaning disc and go again but I would be inclined to go for a "whitebox" drive from Maplin as it is probably as cheap a replacement as you'll get and its the least lost if it proves to be a configuration fault which is unlikely in my opinion
Kenny F
December 2008