Occasionally (At least once a week), the ability to type characters within any application disappears! Also, when I try to switch workspaces using the mouse, nothing happens (but I can using a keyboard shortcut). I can't figure out how to reproduce this bug (yet). At the time though, Mozilla Firefox (1.5.0.5), Thunderbird (1.5.0.4) and  a slew of terminals (Terminal 0.2.5.4beta2) are usually open. Finally, when trying to logout of Xfce (in order to reclaim my keyboard), clicking on the logout button causes it to visibly flicker (the button) without doing anything.