Weird Firefox bug?

I run Firefox maximized and last night I found a weird bug. If I have it maximized and try to minimize it to the taskbar it immediately bounces back up. If I have it in a "normal" window and minimize it it works properly. I think this is a new problem (I don't minimize it often) and my best guess is that it started up after the last windows update (earliest), my adding the ImageShack toolbar to IE7, or I updated the LittleFox theme and Dictionary Search add-ons (latest).

Anyone else having this problem?