For every new iMovie project, you also have to choose a frame rate
- 30 FPS NTSC
, 25 FPS PAL
or 24 FPS cinema.
If you're in North America or have a camcorder made there, you'll want NTSC. If you're in Europe or have a camcorder made there, you'll want PAL. And if you have a special new camera that records 24 frames per second (you'll know who you are), choose that.