I agree that something is borked there
Is it a fresh install ? or have you made some tweaks and experiments ?
By the way, i propose you open synaptic (sudo apt-get install synaptic), search for:
- ubuntu-desktop : uninstall it for now
- compiz : uninstall ALL the related packages (*compiz*)
- unity : uninstall them all also
- install unity (which is by default the 3D)
- or install unity-2d
Thats it, now logout/in again, and watch the difference (if any)
If the system is loading less gnome-session than previously, and are satisfied, then reinstall ubuntu-desktop.