Hey! Sorry about the bug.. This seems to be something happening to a lot of OSX users:
In your "/Library/Logs/CrashReporter" directory there should be a crash log for After Effects that could fill me in on specifically what is going wrong.
This crash log does not appear to make any mention of PixSort though this cautionary event log does mention the that your system is experiencing an excessive 45199 "wakeups" per minute which appears to be mostly safe. Do you have another crash log that you are able to send? Possibly the one immediately before this one is the actual crash-event log.