Every time I open firefox I get msg "the update could not be installed, please make sure no other copies are open and restart firefox"

Try to run the Firefox program once as Administrator (right-click: Run as Administrator). If that doesn't work then try to boot the computer in Windows Safe Mode with network support (press F8 on the boot screen) and the above again (run Firefox once as Administrator). *http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/