[Adrian Zambrano]

I had this happen after opening a project that had worked before upgrading to leopard. I had tried trashing AE preferences which didn’t work. After seeing others post their solution as re-installing the OS I felt discouraged. The fix is actually to update Quicktime to the latest version since it has been fixed to work with AE. I figured there was a relation between AE and QT considering the formats AE outputs as well as how much QT has affected AE recently. I hope this helps!