The Firefox UI is periodically freezing. I haven't managed to blame something in particular, though it's possible it happened after I installed the latest version of flash through "Flash-Aid".
During these Firefox freezes, the menu works, but the general UI does not. Mousing over buttons produces no effect, and the mouse can't interact with the page. The only part that works is the minimize, maximize, restore, close buttons, and the menus.
Since the menus work, I can open a new window and continue my browsing without closing firefox.
I can also tell it to open a new tab, or to open a file.
If I open a new tab, the display view (where the page is displayed) reacts as if a new page is created, and the cursur shows up in the address bar. However I can't type in the address bar, and the UI is still frozen.
If I open a file, again, the display shows the new file, but the UI is still frozen and the mouse can't interact with the text from the file.
Sometimes if I "restore" the window (dragging the menu bar down), and them maximize it again, it fixes. Sometimes it doesn't.