After rebooting Ubuntu 12.04.2 LTS i unexpectedly saw menu bar not in the top (as always) but in the bottom. 'Hidden' menu bar in the top are still working, e.g. i can restart operating system. See screen:
Also keeping mouse on the side bar makes it black (i can't make a screenshot because when i click PrtSc button all screen becomes black). Any suggestions?
PS: before this i installed kvm packages, don't know if it can help (i haven't been rebooting for a long time so i'm not absolutely sure that it's a reason).
Before posting question i tried this:
sudo apt-get install --reinstall unity sudo apt-get install --reinstall ubuntu-desktop
But it didn't help.
UPDATe: Issue was resolved. Thanks to @bain,
apt-get update && apt-get dist-upgrade works perfect!