I'm using Ubuntu 11.04 (upgraded from LTS 10.04) and Firefox (version 11) doesn't show it's icon in the Window List panel, in the Firefox window top left corner (system menu) nor when using ALT+TAB to switch applications.

I'm using unity 2D since I'm running ubuntu as a guest in a VMWare virtual machine (Host is windows 7)

Instead of the Firefox icon I get what appears to be a generic icon that looks like an app window in the window list and a black rectangle with a curl in the bottom right corner in the ALT+TAB window.

How do I fix this so that the proper Firefox icon gets displayed?

EDIT: Depending on the icon set chosen in the Appearence settings window sometimes I get the icon, sometimes I don't. When using Ubuntu classic none of the icon sets provide the icon for Firefox.