You can only create or open a project in iDVD if the region code has been set on your computer.
The first time you play a DVD on your computer, your optical drive is set to the region code of the disc. The drive's region code restricts DVD Player to playing discs with the same region code or with no region code.
If you are unable to create a new iDVD project or open an existing project you must set the region code for your optical drive.
Note: You must have a display connected to your computer. If you plan to run the computer without a display attached ("headless"), you will need to connect a display in order to initially set the region code.