It seems that the Firefox updater has some glitches updating the software when less-privileged users and Admin users are concurrently accessing it via terminal services.
I noticed this last week when the auto update for 2.0.07 started. Because there were concurrent users logged in at the time, only the Admin instance of the application was updated successfully. Here is the screen shot of what you get for a non-Admin user:
And no matter how many times you reboot the machine, this message remains for the non-Admin users. I guess I will have to install Firefox to get rid of this problem…