What is on the additional pages? ads? Is this with many websites, some, a few? Many site issues can be caused by corrupt cookies or cache. '''Warning ! ! ''' This will log you out of sites you're logged in to. You may also lose any settings for that website. * [https://support.mozilla.org/en-US/kb/delete-cookies-remove-info-websites-stored Delete cookies to remove the information websites have stored on your computer] {web link} * [https://support.mozilla.org/en-US/kb/how-clear-firefox-cache How to clear the Firefox cache] {web link} If there is still a problem, '''[https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode Start Firefox in Safe Mode]''' {web link} by holding down the '''<Shift> ''(Mac=Options)''''' key, and then starting Firefox. A small dialog should appear. Click '''Start In Safe Mode''' (not Refresh). Did this help? While you are in safe mode; Try ''[https://support.mozilla.org/en-US/kb/forum-response-disable-hardware-acceleration disabling graphics hardware acceleration]'' {web link} in Firefox. Since this feature was added to Firefox it has gradually improved but there are still a few glitches.

Many web sites. Why should all my cookies suddenly be corrupted?

I just closed this page and a BLANK TAB took its place!

You may have ad/mal-ware. Further information can be found in this article; https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware?cache=no Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.

I was not thinking its malware, because it started happening right after a Windows update. I uninstalled the update, but the problem has persisted.