uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files and C:\Program Files(x86) Then restart system. Then run Windows Disk Cleanup. (Note : This should be Pinned and run weekly, If never done below expect 10's of gig's) Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved. But you should make a back up before you do : https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles Reinstall with Current Release Firefox 57.0.2 with a Full Version Installer https://www.mozilla.org/firefox/all/ Please let us know if this solved your issue or if need further assistance.

''nonimarie [[#question-1194303|said]]'' <blockquote> firefox will not open when the icon is clicked on. ... it spins for about 3 seconds and nothing happens.</blockquote> If you try again right away, does Firefox say it is running and needs to be closed first, or does it behave like it's not running? Perhaps you're encountering this issue: '''''A Recent Issue for 64-bit Windows Users with 64-bit Firefox''''' Before Firefox 56.0.1, users of 64-bit Windows generally were using the traditional 32-bit version of Firefox. However, newer versions may switch you to the 64-bit version. We received a number of puzzling reports of Firefox either not starting -- the way you described -- or not loading any pages after this migration. One user discovered that Windows was silently killing Firefox at startup and recording it in the Windows event logs (you can view event logs using the Event Viewer). Based on one of the reports in the log, we were able to trace that to an out-of-date Logitech camera driver, of all things. By now at least six other users reported that uninstalling or updating the Logitech camera software resolved their problem as well. * https://support.mozilla.org/questions/1179822#answer-1019375 * https://support.mozilla.org/questions/1181740#answer-1021470 * https://support.mozilla.org/questions/1181405#answer-1022798 * https://support.mozilla.org/questions/1182572#answer-1023413 * https://support.mozilla.org/questions/1182847#answer-1024290 * ''With 57:'' https://support.mozilla.org/questions/1188971 * https://support.mozilla.org/questions/1191368#answer-1041814 Do you want some assistance in looking at event logs, or do you have such a webcam? ---- If the investigation doesn't yield any solutions, it is worth trying a return to 32-bit Firefox. While normally this kind of change is seamless -- the installer detects your existing data and preserves everything -- you might want to make a backup "just in case." * [[Back up and restore information in Firefox profiles]] * [[How to opt out of 32-bit Firefox migration to 64-bit]] ''Note: If you decide to try 64-bit Firefox on the same system at some point in the future, see:'' [[How to switch from 32-bit to 64-bit Firefox]].