This doesn't happen 100% of the time, but happens probably 50-75%.
The issue is whenever I right-click on an icon on my Unity panel, it causes the entire desktop to freeze. The right-click menu applet (you know where it says "unlock from launcher, etc.") stays on the screen and will not go away. I can still move the mouse around, but my keyboard becomes non-functional. I have to do an X restart to fix the problem. Before I enabled ctrl-alt-backspace, I had to drop to terminal and do a system reboot.
I am using Unity 3D and compiz with an Nvidia graphics card. Has anyone else noticed this problem? I have searched the Ubuntu bug list and cannot seem to find an issue just like this one, though I admit I might have missed it.