Ubuntuzilla is a great way of having your cake and eating it. You can have the robustness of the Ubuntu repository system without foregoing the very best of Mozilla Firefox or Thunderbird (see Getting latest Firefox and Thunderbird on Ubuntu). But I did experience a big problem upgrading to Thunderbird 3.1. Clicking on the Thunderbird icon resulted in … nothing. The reason was that the Lightning extension was now incompatible. Solution?

1. ubuntuzilla.py -a remove -p thunderbird
2. sudo apt-get update
3. ubuntuzilla.py -a install -p thunderbird
4. Download addon for lightning that is compatible with 3.1 e.g. Lightning 1.0b2
5. thunderbird -safe-mode
6. Install new add-on – probably you downloaded it to your desktop
7. Restart Thunderbird