If you have not already figured this out, here is how to force quit an unresponsive application in Ubuntu 11.10.
1. Open Unity launcher by pressing the Meta key or clicking the launcher button.
2. Type “Main Menu” and click on main menu, which should open a new application window.
3. Select “New Item” and enter the following details:
Name: Force Quit or Quit or Shutthef@!#up or whatever you like.
And save the new item.
4. Open launcher and type the name you gave the new item.
5. Drag the item to the Unity bar.
6. Now whenever you have to force quit an unresponsive program, click on the force quit item that you just created and click the unresponsive window you would like to shut down.
That should fix it.