If you get an error message that you do not have sufficient permissions or have other problems with updating to update then easiest is to download the full version and trash the currently installed version to do a clean install of the new version.

Download a new copy of the Firefox program and save the DMG file to the desktop

• Firefox 4.0.x: http://www.mozilla.com/en-US/firefox/all.html

• Trash the current Firefox application to do a clean (re-)install
• Install the new version that you have downloaded

Your profile data is stored elsewhere in the Firefox Profile Folder, so you won't lose your bookmarks and other personal data.

Yeah, I get that, but I do I execute a succesfull and complete de-install? This is what I would do: - search on 'firefox' in 'this computer' - delete everything that comes up - empty waste basket - restart the computer and install ff anew

Please let me know if this is the way to go or wether there's a better method. Thanks for your reply!

You can drag the Firefox application from the doc to the trash to remove (uninstall) it. That should be sufficient and allow you to install the new version with causing problems.

Well thank you Cor-el! I just did what you suggested & things seem to be fine now - keep my fingers crossed... If everything stays in order I'm gonna click the Solved It button. :-)