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 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.

Hi MarsBar, what kinds of functionality are missing?

In another thread, a user reported that in-page navigation menus and mouseover overlays stopped working. That system had a touch screen. Sometimes Firefox will switch to a touch mode and not accept mouse input for certain elements; perhaps the Windows 10 update is triggering that?

Here's where you can find the setting if you want to experiment with it:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste touch and pause while the list is filtered

(3) Double-click the dom.w3c_touch_events.enabled preference and edit the value to 0 (zero) and then click OK. The options are:

• 0 => disable touch
  
• 1 => enable touch
  
• 2 => auto-detect whether the system supports touch (default in Fx52)

I don't know whether that will take effect immediately or after you exit and start Firefox up again. Does that have any effect on how the problem buttons work?

I don't know if this problem still exists, but in the Windows 8/8.1 days, users of HP All-in-One systems also needed to disable "HID-compliant touch screen" in the Windows device manager. Hopefully that problem hasn't come back in a new form with the latest Windows 10 update.

Well things seem to be working properly! I uninstalled and reinstalled as Pkshadow suggested. It seems to have rectified the problem. Could it be that Microsoft is NOT at fault this time. Colour me surprised! My thanks to both Pkshadow and jscher2000 for their assistance.

I am glad to hear that your problem has been resolved. If you haven't already, *Please select the answer that solves the problem*. This will help other users with similar problems find the solution more easily. Thank you for contacting Mozilla Support.