''update failed -- Firefox still running'' Go to the "Processes" tab of the Windows Task Manager since you are on Windows 7 use Ctrl+Shift+Esc and then select the "Processes" tab if not already selected. Right-click of firefox.exe and use "Close tree". Restart Firefox in your normal manner. It is into your current profile that you need to replace with files from the old profile that can only be done with Firefox down. I don't know what you did, so after bringing up Firefox type about:support into the location bar, then use the "Open Containing Folder" button. That is the folder you need to copy your old profile into. Now bring Firefox down with File > Exit or "Firefox" > Exit, do not attempt to close Firefox with the "X" in upper right corner that merely closes the Window. Verify that Firefox is actually down via the Windows Task Manager again and remove the files replacing with your old profile content. Then restart Firefox in your normal manner. You should be set.