I've been having this problem where Firefox just fails to start. I click the desktop icon and nothing happens. No errors, no messages, no window flashes, just nothing. The process does *not* show in the task manager. There are no extensions or themes installed. It does run in Windows safe mode. Firefox's own safe mode makes no difference. The only (very temporary) solution I've found is to uninstall Firefox, delete the program folder by hand and reinstall Firefox. But that only tends to work for a day or so. I've run malware and virus scans on the computer, progressively closed running processes, installed the beta version of Firefox. Nothing works.