I have After Effects CS6, file version (no dvds). Using a 4,1 Nehalem Mac Pro, Snow Leopard, w/2 x 2.6 GHz quad core Intel Xeon, 18GB RAM, NVIDIA GTX285 card. A few months after installing AECS6, I bought an internal hard drive and put OS Mountain Lion onto it. When I try to open AECS6 after booting from the new hard drive, I get a series of error messages including "Quicktime is not installed" and "unknown error". The program crashes before opening. It still works fine on the original hard drive w/Snow Leopard. I've googled and found a lot of suggestions for helping AECS6 start in Mountain Lion after the "Quicktime is not installed" error message, but none of them seem to work for me. And I'm not sure that it isn't related to the partition. I copied the root AECS6 folder into the new hard drive's Applications folder, still get the same errors. Quicktime 7 and 10 are installed on both drives, along with the appropriate codecs. I know that the codecs are properly installed on the new drive because Nuke can access them.