When Firefox is launched, a Finder Message reads: "The application “Firefox.app” can’t be opened." After problems with Firefox (possibly related to Kaspersky Internet Security software), I finally resorted to: a) uninstalling and deleting all Kaspersky software (which had no effect), b) deleting all Firefox and Mozilla files, and c) reinstalling a new downloaded version of Firefox. Firefox still will still not launch when the Firefox icon in the Applications folder is clicked. The so-called safe-mode launch is not available when the Option key was used for launch. I can launch the new version of Firefox using a Terminal command (which also restores previous in-use windows and website pages that were in use), but no web pages will load anyway.