You are a genius! I have had endless trouble trying to use iDVD because every time I inserted a blank CD or DVD, Toast launched. To overcome the problem I used a different start up disc on which Toast was not installed.
Trying to find an answer to the problem I eventually arrived at your suggestion.
The strange thing is that no text appears when one clicks on "Toast launches when inserting a blank CD/DVD" which is on this page:-
I have never thought to look in System Preferences! Thanks.