Comment 5 for bug 290077

I experience something similar on Ubuntu Intrepid FF3.0.5 with all add-ons disabled. The submenus on the bookmarks toolbar don't open when I want to drag an entry (ie. new entry from address bar) into it. Firefox freezes, the dragged entry is being displayed one and a half times (in place), and the mouse is frozen to drag mode. Everything I can do is switching to tty1 and killing firefox from the console.
I'm pretty sure this is reproduceable.