I keep getting the "The update could not be installed. Please make sure there are no other copies of Firefox running on your computer, and then restart Firefox to try again." message. My solution has been to stop Firefox and then use Internet Explorer to download and install new version. I would now like to sort out this problem. System: Vista; Firefox 3.6.10 installed. I go Program Files > Mozilla Firefox > Firefox.exe and 'Run as Administrator'. Under 'Help' I click 'Install downloaded Update now.' All I get is the same 'Update could not be installed' message. Also tried: As Administrator stopped Firefox, rebooted; got same message when opening Firefox. I had one message that Ancestry.com Advanced Viewer was not compatible with FF 3.6.11, but uninstalled the Ancestry viewer some time ago. Any suggestions, or must I carry on using I.E to download new versions?