Thanks for the link. It did point out several files that AppZapper missed when I deleted Compressor for a reinstall. Unfortunately it still doesn’t help. I deleted all Compressor, Qmaster and Motion files per the tech doc, then had to reinstall all 8 disks of Final Cut Studio 2 (once more, it wouldn’t let me install only Compressor; instead I had to install everything all over again). Even the older install version of Compressor (3.0) doesn’t work, which leads me to think it has nothing to do with using QuickTime 7.4 but is something else entirely. At this point I don’t know what to do except backup all my files, erase the hard drive, and reinstall Leopard and all my apps, updating everything except QT which I should keep at 7.3 if I want to render After Effects comps. Anyone has any other suggestions perhaps? I’m running a dual 3GHz Mac Pro with 8GB of RAM so speed and memory should not be a factor.