Thanks, Tsantee. I haven't tried saving as Disc image then burning but will try next time. Need new discs anyway, as this problem used up my last few.
Re trashing plist, I do not find anything at all for Toast (or Roxio) in the Preferences folder of user>Library>Preferences. Doesn't seem to be very complete as to applications (see image attached) but I find no other library except system library with no preferences folder. Any suggestions??
This is only third day I am trying to set up my new iMac with Lion and so far have many questions about changes, things no longer covered, etc. Apple Support, of course, disclaimed any knowledge or responsibility for this Toast problem or any other of the minor questions I reported yesterday.