Every time I type something from my history or bookmarks into the address bar, it displays the first character or two, then refuses to display the rest of the site address that I am typing and fails to display results from my history/bookmarks. It only displays what I am typing after I press Esc or click somewhere on the webpage. A similar problem also occurs when I attempt to retype something in a website form, including the forms on this very "edit a question" page, except the autocomplete results display and I can manually use my mouse to select what I wanted to type. I'm guessing that autocomplete is locking up for some reason. However, I've tried cleaning the sql databases and have even removed the profile folder and reinstalled firefox, to no avail. An inconvenient workaround I know of is to run firefox in safe mode and disable all addons or reset all user preferences to defaults, which makes autocomplete behave exactly as it should until I close firefox. I can reenable my addons and restart firefox and the location bar will continue to behave properly, but closing and reopening firefox without using safe mode, even if nothing is changed (addons reenabled, preferences set, etc.), results in autocomplete not cooperating again. This problem began about a month after I had upgraded Xubuntu to 11.10.