why is it necessary for me to reinstall firefox every morning when i turn my computer on?

Every morning when i turn on computer, i must reinstall firefox. Clicking on the icon in my lower tray, or clicking on the exe file on desktop do not work. In order to use firefox, i must remove program (ctl panel) and reinstall *every* morning. Why? And what can i do to avoid this, please? == This happened == Every time Firefox opened == i initially installed firefox == == User Agent == Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/532.5 (KHTML, like Gecko) Chrome/4.1.249.1064 Safari/532.5