Same problem for me (Ubuntu 9.10 + Firefox 3.5.7 on Acer Aspire One 110, intel GMA + Compiz).
My work around is to open an new window and then closing it (ctrl+n, ctrl+w). After that auto completion starts working again in my original window. (The new window opened also has working auto completion, but I'm a single window, multiple tabs man, so I close it).
Same problem for me (Ubuntu 9.10 + Firefox 3.5.7 on Acer Aspire One 110, intel GMA + Compiz).
My work around is to open an new window and then closing it (ctrl+n, ctrl+w). After that auto completion starts working again in my original window. (The new window opened also has working auto completion, but I'm a single window, multiple tabs man, so I close it).