You might try trashing the iMovie preferences, shutting down, restarting your computer with the ZR50 attached and "on". Then start iMovie. Make sure there are no other FW devices that handle video or sound connected and that the FW connection for the camera is direct( eg. not through a hub). The ZR 50 is not that different than the previous models. Canon tends to be touchy as a camera. You also could use QT 7.0X as a test to see if your camera can communicate with your computer. There are other posts on this Forum about how to handle DV cameras, like Canon's, that are "touchy".