Hi, Is this happening on certain sites/content?? You can consider the [https://support.mozilla.org/en-US/kb/reset-firefox-easily-fix-most-problems Reset Firefox] feature via '''Help''' ('''Alt''' + '''H''') > '''Troubleshooting Information'''. If the problem persists, you can also temporarily '''Disable''' the '''Plugins''' in '''Tools''' ('''Alt''' + '''T''') > '''Add-ons''' to check. (To revert to the previous profile you were using, close the new profile (i.e. exit Firefox), start Firefox and choose the '''Default User''' profile. While the [https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles Profile Manager] is open, you can also delete the newly reset profile (the one containing random numbers), or the former profile, as the case may be). If the reset is okay, it would be a good idea to delete the old profile as otherwise it would be left intact with the previous data until deleted. [https://support.mozilla.org/en-US/kb/Managing-profiles Managing profiles] [https://support.mozilla.org/en-US/kb/Profiles?s=profile&r=2&e=sph&as=s Profiles Howto]

To clarify, this is happening regardless of what tab I'm on (though it could be one of the tabs I've left open while trying different things) disabling Add-ons fixes things though.

You can now try to narrow it to the exact add-on that may be causing this, and try to update it, or keep it disabled. You can also post the result, there could be workarounds for a specific add-on in some cases.