I have become aware of this today, and seeing how many EIAS users are Adobe After Effects ones, too…
It seems Quicktime 7.4 breaks After Effects movie rendering. In this Apple forum thread the issue is discussed, including some means of reverting to older versions of Quicktime:
http://discussions.apple.com/thread.jspa?messageID=6391144
Also Adobe just released AE 8.0.2, which won’t solve the issue anyway:
http://blogs.adobe.com/davtechtable/2008/01/aftereffects_cs3_802_update_is_1.html