Running 12.04 on a thinkpad T520 with nVidia NVIDIA Quadro NVS 4200M graphics. Just updated to the lasted nvidia 310 driver. Everything works great. However, as soon as I attached an external monitor using nvidia twinview, compiz features such as scale (moves all the active windows in one page) stopped working, as well as alt-tab to list all opened programs. Any ideas how i can fix this? never had this problem with 11.04. I can post my xorg.conf if that's of use to you. Thanks much!
edit 1: I am using gnome3 classic
edit 2: alt-tab works -- compiz application switcher (by default for gnome3 / unity) will crash gnome-classic, by changing to "static application switcher" in compiz seemed to solve the problem, but the scale still does not work when an external monitor is attached.