I'm using Firefox 6 on Windows XP SP3. I normally log in as a limited user and use the Admin account for installing.

Some Firefox and Thunderbird updates have failed to fully update. I'll run the programs as Admin or log in as Admin and run the updates. The programs update successfully under the Admin account, but when I switch back to the limited account, it tells me the update can't complete. When I check Help > About, it shows the updated version number. The only way I've been able to get rid of the message, is to change my normal account to an administrator, start Firefox so the update completes, then change the account back to limited. This doesn't happen with every update. The update to Firefox 6.0 is one of the problem updates.