I have a 1ghz power pc iMac. Recently, when I import any .w4p (AAC) audio file purchased from Apple store and drop it on the audio timeline in ImovieHD, the video drops frames and stutters/stalls bad. If I drop in an .mp3 audio, everything works fine. I have reinstalled Itunes, Imovie, Ilife, Quicktime and even reverted to Itunes 7.0 with the same result. I have been converting my purchased songs to .mp3's, but it is a tedious process. Does anyone have a solution for this?