Not sure what causes this. Switched to Ubuntu 11.10 recently, haven't worked out all the kinks. Basically, after a certain period of time with the system running, possibly after having something open in fullscreen mode, the dock and the alt+tab application switcher both appear under all applications, making them utterly useless unless I minimize everything just to be able to see them. The dock also appears to have stopped retracting. Any ideas? A restart fixes it, but only for so long.

EDIT: Running "unity --replace" seems to fix it, though it can still re-break.