It may be that you don’t have to reinstall iDVD. You can try and delete the preference files and the cache and see if that helps.
Deleting preference files is a typical first thing to try with a program that quits as soon as you start it, or when the icon just bounces in the dock and doesn’t do anything else, or won’t let you save settings.
Almost all programs have preference files to store settings and configurations; some programs have cache folders, too, which store copies of files and temporary settings. When programs don’t start up or do what’s expected, sometimes it is as simple as the preference file being corrupted somehow, and deleting can help because the program will make a fresh copy of a missing preference file on starting up. You’ll loose settings and other customizations until you reenter them in the new copy of the preference file.
Preference files are located in either HardDrive/Library/Preferences/ or HardDrive/User/Library/Preferences/. See the difference in those directory paths? “User” is the name of your account. Some programs will have preference files in both locations.
Preference files usually have a suffix of “.plist” or might be called “preferences,” depending on the manufacturer. Most Apple program preference files are named like com.apple.nameofprogram.plist, so they’re easy to find.
For other programs, preference files can be named com.google.nameofprogram.plist, com.intuit.plist, etc. Still other preferences can be in folders titled with the name of the program inside the /Library/Preferences folder. Look around and also Google the name of the program and “preference” or “settings” and often you’ll zero in on a support post on a Web site that will help you.
Caches are located in HardDrive/User/Library/Preferences/Caches/ . (There are also cache folders in HardDrive/Library/Preferences/Caches/, but they are typically for system programs and you don’t need to mess with them.
If the program you’re deleting the preferences for is registered and requires a serial number, be sure you have that serial and registration information in hard copy before you delete the preference file, because some preference files hold registration information and you might have to reenter it after you start the program again. But for iDVD, that’s not a concern.
To delete the preference files and caches for iDVD, first, quit iDVD.
For iDVD, there can be two plist files, one in HardDrive/Library/Preferences/ and one in HardDrive/User/Library/Preferences/ and the files are called com.apple.iDVD.plist. Drag both of them to the trash.
And then delete the cache folder in HardDrive/User/Library/Preferences/Caches/
Empty the trash and try iDVD again. It should work OK. If not, something else is wrong. Try updating your system software with Software Update and see if that helps.