If you see the message, XULRunner - Error: Platform version <x.x.x.x> is not compatible with minVersion <x.x.x.x> .... after a Software Update ("<x.x.x.x>" depends on version number),
use another browser to download the Firefox installer from mozilla.com, save it to the desktop or other location, and then delete the Firefox installation directory and reinstall Firefox. For detailed instructions, see Standard diagnostic - Firefox#Clean reinstall. This problem is sometimes caused by a security program (such as Zone Alarm Extreme Security, see below) that is preventing changes to the "application.ini" file when you update Firefox. [7] [8] [9]

