Thanks, Jim! After staring at my recalcitrant iMovie application with a blank expression, it suddenly hit me that this was not the same programme as the iMovie on my PB (on which I later installed the 05 iLife Suite). Apparantly when I transferred my personal data onto my new iMac using firewire, the 04 iMovie version went with it. Strange, because none of the other 04 iLife applications made the jump. In iPhoto, for example, all my photos were automatically placed in the 05 Edition. So I located the iMovie HD icon deep within the bowels of my Applications Folder, where it was snuggled up next to the 04 iMovie icon. Managed to transfer all my widescreen footage to the HD version, not entirely smoothly as they now playback with all sorts of unexpected breaks and pauses.