#6 - July 27, 2010, 6:23 a.m.
This does sound like misbehaving or out of date addons.
I'd recommend starting with a full reset UI - do NOT reinstall/enable any addons and see if this persists. If that resolves this, check for newer versions and I'd troubleshoot by installing them back one at a time.
To do a full reset UI, you will want to save your addons in another spot if you wish to preserve them.
Then rename/delete or move your WTF, Cache and Interface folders while WoW is shutdown. Reboot your system.
Note, if you are running Vista make sure your permissions are set so it does not undo your changes.
More detailed instructions for different operating systems, including Macs are here.
http://us.blizzard.com/support/article.xml?articleId=18761&searchQuery=reset%20UI&pageNumber=1