Hi, If not a need to be running ver 59 as it is a Beta/Alpha then should not be running it. Also all bugs should be reported : If you have a bug, file a bug report. https://bugzilla.mozilla.org/ Bug Writing Guidelines : https://developer.mozilla.org/en-US/docs/Mozilla/QA/Bug_writing_guidelines Current Release is 58.0.2 for Firefox and Developer Edition is 60.0b1 Please : 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 *https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer Reinstall with Current Release Firefox 58.0.2 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.