Quote Originally Posted by jrefl5 View Post
I have seen it a few times also. Running Firefox 2.0.0.12 & Zimbra 5.0.2.

I'll start watching for a pattern.
Looks like you're seeing this bug: Bug 24231 - Hourglass cursor flickers endlessly when replying to message

Its been fixed but you'll have to wait for 5.0.3 :/