User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.16) Gecko/20080702 Firefox/2.0.0.16 Build Identifier: 2.0.0.9 / 2.0.0.14 / 2.0.0.16 We had version 2.0.0.9 installed and hit the infinite loop of updating and failing on one account on the machine. We downloaded the latest version (2.0.0.16) and installed it. Things worked fine. That user logged off and the other user logged in to the machine (WinXP) and the updater was halfway through downloading version 2.0.0.14. It finished downloading that version and installed the "update" regressing the machine from 2.0.0.16 to 2.0.0.14. Reproducible: Didn't try Steps to Reproduce: 1. I don't know if it is already fixed, and probably can't reproduce it myself because the updater would detect and download the latest version, not a version two versions back to automatically download. It is probably a rare test case, but should be fixed. I would have to install version 2.0.0.9, find an update site to point to that had version 2.0.0.14 and figure out how to point the automatic updater at that site and then while one account was downloading the 2.0.0.14 version install the 2.0.0.16 version manually in another account. Then the first account would finish the download of the 2.0.0.14 version and install that overtop the 2.0.0.16 version. 2. 3. Expected Results: The Updater should detect if the same or a more recent version is already installed.

Moving this to Toolkit / Application Update as that is the component where this should get the best attention.

Yep, just had firefox automatically install version 3.0.1 over the top of version 3.0.3. Didn't seem to be any way to stop the automatic update mechanism once it had the bit in its teeth. Guessing somewhat, I suspect the update functionality started ages ago within an account that is less frequently used on the machine in question and didn't complete. Meanwhile more commonly used accounts installed later versions of the software before the lesser used account was once again used and the auto update continued from where it left off months ago and finally completed.