Comment 2 for bug 999020

I have also encountered this problem after upgrading to Thunderbird 12.0.1 on Lucid 10.04, kernel 2.6.32-41-generic.

The bug description matches my experience. Menus will display but disappear before they can be clicked on. This can happen several times a day and is not fixed until the program is restarted.

Thunderbird has been the only program on the system to exhibit the behavior.

The system is up to date for 10.04.