• Either an old project is corrupted or interferes - or -
• the free space on Start Up (Mac OS) Hard disk is too low - or -
• You moved over the iDVD application from an old Mac to a new one
(this doesn't work so - it must be installed in the right way (from DVD))
Free Space - I never let go less than 25GB - EVER - and it's just this hard disk that matters !
If OK then try
Start iDVD - BUT KEEP alt-key down during the full Start-Up process.
Now select a Brand New iDVD project - DO NOT open an old one
That's what I can figure out - BUT it can be something completely different as I know nothing about.
Yours Bengt W