I put a project--including all media--on an external drive. One of the media files is a 1.1 MB m4a. I connected the drive (via FireWire) to the iMac, and opened the project. Everything ran fine. I then connected the drive to the MBP. Most of the project is OK, but running that one m4a (and its subclips) on the source monitor and the timeline plays a corrupted sound: it seems to skip about half.
Playing the m4a on other apps, such as iTunes or QuickTime, on either machine, shows no problem. Also no problem, inside Premiere Pro or outside, with other, shorter m4a clips. I converted the m4a to a mov file and imported to Premiere Pro on the MBP; no problem.
Is there some m4a/Premiere Pro "gotcha" I should know about?