This is very likely a known issue, which makes the application crash on exit when script panels are docked.
Check this technical support document to see if this is indeed the cuprit and how to avoid it.
If this is the problem you're experiencing, the AE team is working on a solution.
BTW, thanks for filing the data in Adobe Crash Reporter and sending it.
Thanks Todd, so far that seems to be the fix. I was using a background render script that was docked.
After upgrading to version 184.108.40.206 when rendering AE CS4 crashes.