Yes, I had a problem with the update to Firefox 3.6.7 --- a first time ever occurrence for me in many years as a Firefox user. I kept getting the message that another copy of Firefox was running, carefully investigated and determined that was not the case. The developers need to look at this problem immediately!

I downloaded the full installer, saved it to my hard drive, ran the installer and the problem was solved.

Download from here: http://www.mozilla.com/en-US/firefox/all.html

See: http://support.mozilla.com/en-US/kb/Installing+Firefox

I have a solution...for finding that other existance of a firefox running..

I am using Windows Vista.. I had the problem with 3.6.7 update not installing. Got window saying that another existance of firefox was still running

I found a firefox container after looking in Control Panel then Under Programs - Change startup programs which opened my windows defender. In the Catagory Box I selected Currently Running programs found under - Mozilla Corporation Heading existance of 2 running softwares by Firefox. Firefox 2404 - Firefox.exe and firefox 2992 - plugin-container.exe

I ended both processes which shut both down

then restarted firefox and the update ...was made and done

I hope this helps someone

I hated to download en install a new Firefox, because Favourites and History will be lost.

I solved the problem this way: 1. Find the *.exe files in the folder C:\Program Files\Mozilla Firefox. 2. Change the extension of updater.exe. This will result in ending the loop. 3. Restart Firefox. The old version 3.66 will restart.

Now I can save my favourites and history, for the case this happens again. But until now Firefox continues working perfect.

Supplement to my former post:

I forgot to mention: 4. Restore the extension of updater.exe !! Or else new updates will fail.

See http://kb.mozillazine.org/Software_Update (Software Update not working properly) Remove the files in the updates and updates\0 folder: XP: C:\Documents and Settings\<user>\Local Settings\Application Data\Mozilla\Firefox\Mozilla Firefox\updates %USERPROFILE%\Local Settings\Application Data\Mozilla\Firefox\Mozilla Firefox\updates C:\Program Files\Mozilla Firefox\updates ..... Vista/Windows7: C:\Users\<user>\AppData\Local\Mozilla\Firefox\Mozilla Firefox\updates %LOCALAPPDATA%\Mozilla\Firefox\Mozilla Firefox\updates C:\Users\<user>\AppData\Local\VirtualStore\Program Files\Mozilla Firefox\updates