I'm on a PC, so I don't know of the issues exactly, but a buddy of mine had to buy a new Mac to run CS6 a couple years ago, becuase it required the 64bit OS. Just thinking outloud, but is there a chance that the 64bit OS you're likely on won't support that old of software on 32bit?
Hope you find some answers!
What operating system are you using?
Thanks for your input/response. Much appreciated. If that is the case, then I'll have to sell AE7 and go for a version that works on OSX 10.9.1.
After Effects 7 was created nearly a decade before Mac OS X v10.9 was released, so there was no way that we could have developed and tested that version of After Effects for that version of Mac OS.
You will need to use a more recent version. See the system requirements: