I'm not too expert of Ubuntu, but after a quite painful upgrade to version 12.04 (from 11.10), which first required to reinstall wireless drivers in order to work properly, and after an update from the Update Manager that I ran soon after the upgrade, I have a very strange problem coming up: at login page, where you choose your user among the list of the available ones, I can also see the list of available IDEs (Gnome, Gnome classic, Unity, Unity 2d, etc) but the funny thing is that the classic "foot" logo normally associated to the GNOME selection has now disappeared, and instead the "gear" logo (the one normally related to Unity, is on the side of the "gnome" choice. Note that the foot logo remains associated to the Gnome Classic item, and that the "gear" logo is still associated to the various versions of Unity available. This is not serious, since I can still access my GNOME or Unity environment, but I wonder if I can fix this up.