I just upgraded to Mountain Lion and now, though I have the icon for idvd and the bar at the top of the page, it won't open. Any suggestions? Thanks.

Try this basic troubleshooting fix:

1 - delete the IDVD preference file, com.apple.iDVD.plist, that resides in your

User/Home/Library/ Preferences folder.

2 - delete IDVD'S cache file, Cache.db, that is located in your

User/Home/Library/Caches/com.apple.iDVD folder.

3 - launch IDVD and try again.

NOTE: In Lion and Mountain Lion the Home/Library folder is now invisible. To make it permanently visible enter the following in the Terminal application window: chflags nohidden ~/Library and hit the Enter button - 10.7: Un-hide the User Library folder.

OT

I have been using iDVD in Mountain Lion just fine, burning 5 dvd's for a big project last week. I just did software update 10.8.4 and now my iDVD launches, but no project window. I've tried the DVD project I just created last week, and tried creating new ones. The icon sort of "blinks" but does not open my project. I could not find the com.apple.iDVD folder or .plist even with spotlight.

NOTE: In Lion and Mountain Lion the Home/Library folder is now invisible. To make it permanently visible enter the following in the Terminal application window: chflags nohidden ~/Library and press the Return key - 10.7: Un-hide the User Library folder.

Once you make the library visible you'll be able to find and remove those files.

I found the Library file. Looked in Preferences folder and Cache folder. com.apple.iDVD or.plist. Is there a seperate Library file in User Home? Where is the Terminal application window?

I found it! And it worked. Googled user library in Mountain Lion, it showed the whole process. Thanks Mr. Toad!