#31 - Nov. 9, 2010, 6 a.m.
This has been an issue since the patch, but resetting of the UI is almost a universal solution.
With the last patch, most older addons are either not going to work, or experience oddities. I'd recommend a full reset and testing this prior to putting ANY addons back in.
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