If there's any common wisdom at all about iMovie, here it is: a pair of golden rules that will stave off a huge number of problems down the road.
Use the latest version . Each ".01" or ".02" upgrade zaps a whole host of bugs and glitches. These updates are free, so when your Software Update program advises you that one is available, jump at the chance to install it.
Set your camcorder to 16-bit audio . The typical digital camcorder can record its audio track using either 12-bit or 16-bit audio. The factory setting is 12-bit, which gives noncomputer owners a chance to overlay a second audio track without erasing the original camera sound. Trouble is, 12-bit audio may slowly drift out of sync with the video when you burn the finished project to a DVD.
Use your camera's menu system to switch to 16-bit audio. You, an iMovie aficionado, can easily overlay additional audio using your computer, so you give up nothingexcept a lot of frustration. (Make this change now, before you record anything important.)