Hello,

Please try using task manager to kill firefox. https://support.mozilla.org/en-US/kb/firefox-already-running-not-responding?redirectlocale=en-US&redirectslug=Firefox+is+already+running+but+is+not+responding#w_use-the-windows-task-manager-to-close-the-existing-firefox-process

Try to start Firefox in Safe Mode to see if that works.

• Windows: hold down the Shift key while starting Firefox
• Mac: hold down the Options key while starting Firefox

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode

It is possible that security software (anti-virus, firewall) is causing the problem. Try to disable security software temporarily to see if that makes a difference.

Try to boot the computer in Windows Safe Mode with network support (press F8 on the boot screen or hold down the Shift key).

• http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/
• http://www.7tutorials.com/4-ways-boot-safe-mode-windows-10

I've been around the houses a few times, as I can't open the Firefox page but eventually the Firefox profile appeared on Task Manager and I closed it. Unfortunately, I still can't run my downloaded Firefox Installer.exe file as the 'Please close Firefox to continue' message appears. Another file called Feedback has also disappeared rather strangely-I don't know how.

HI, please grab a copy of your Profile

• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

Then download Current Release Firefox 59.0.2 with a Full Version Installer

• https://www.mozilla.org/firefox/all/

Then boot into Windows 10 Safe Mode

• https://support.microsoft.com/en-ca/help/12376/windows-10-start-your-pc-in-safe-mode (Do Not Need Networking )

Please uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files , C:\Program Files(x86) & C:\ProgramData 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.

For the future always :

• 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

Please let us know if this solved your issue or if need further assistance.

Note fyi : check to see if have Microsoft update KB4093105 700megs If not you can get it here : https://www.catalog.update.microsoft.com/Search.aspx?q=kb4093105 Note fyi : Windows Spring Update out April 30th so back up stuff you want to save to another drive. https://www.windowscentral.com/microsoft-announces-windows-10-april-2018-update