I am utterly ashamed at how some people are. People need to get over themselves and understand that they are running PREVIEW software that is designed for developers to test on. Sure, Mavericks is running MILES better than Mountain Lion ever did, but it doesn't mean that you can just go ahead and make it your main production machine.
If stuff isn't working, don't assume that developers are going to make a fix for it when it's probably going to conflict with something else in a future beta.
IMPORTANT: The After Effects CC (12.0.1) update fixes a crash on Mac OS X (v10.9). There is no need to install this update on any other operating system. After Effects CC (12.1) is coming soon for all operating systems and includes this same fix plus many more features and bug fixes.
Adobe After Effects CS6 (11.0.3) was released a little while ago with this fix, plus fixes for many other crashes and bugs. Details: http://adobe.ly/AE_CS6_1103
important notes about the After Effects CC (12.0.1) update for Mac OSX v10.9:
Be sure that you are signed in and have activated the softwarei.e., ensure that you are not running After Effects in free trial mode. The update will not work if you are running the application in trial mode.
This update is only available as a manual download (not through the Creative Cloud automatic update mechanism) to prevent users on versions of Mac OS X other than v10.9 (Mavericks) from installing it unnecessarily.