I’ve run into this error message a few times now when Thunderbird chooses to automatically update itself on Windows XP and Windows Vista machines:
“Software Update Failed
One or more files could not be updated. Please make sure all other applications are closed and that you have permission to modify files, and then restart Thunderbird to try again.”
It certainly isn’t a consistent problem that I’ve been running into, but every once in a while on a variety of machines, I’ve received the above error sending Thunderbird into an infinite loop of trying to update and failing. The Mozilla forums lead me to believe that there is some problem with Logitech QuickCam software’s interactions. The consistent solution I have found is to rename this file:
C:Program FilesMozilla ThunderbirdmozMapi32.dll
You can rename it whatever you want. I chose to rename mine to mozMapi32.crpt. As soon as I did that and clicked try again on the update error message Thunderbird successfully went through the upgrade and the problem went away. The update will create a new mozMapi32.dll without issue. You can’t delete the problematic .dll for the same reason the update can’t get past it. I tried unregistering the DLL, but it still didn’t get me past the problem. Renaming the file has consistently worked, or you can uninstall Thunderbird and re-install it to the newest version, but that leads to more complications with the profile remembering that it wants to upgrade next time it starts up. You might try using Unlocker on this DLL to free it up for deletion or unlocking it in the first place instead of renaming it.