I also have the same problem on IE 11. I continue to have the same problem even after trying all the above fixes on both browsers. Any more ideas I can try? Is it possible that having the two browsers loaded though not active at the same time could cause this? I know Avast and AVG Free won't play nicely on the same system even if one is inactive.

Multiple browsers shouldn't be a problem -- most people who have Firefox have at least one other browser (IE on Windows, or Safari on Mac), and often more (e.g., Chrome, Opera...).

The message to update to a compatible browser is unusual. It might be based just on how Firefox is identifying itself or it could be based on something being blocked that the site is trying to use. Since this affects multiple browsers, could it be something your security software is filtering out?

If you use extensions ("3-bar" menu button or Tools > Add-ons > Extensions) that can block content (e.g. Adblock Plus, NoScript, Flash Block, Ghostery) then make sure such extensions do not block content. There is security software that can interfere with loading content, so check that as well.

Start Firefox in Safe Mode to check if one of the extensions ("3-bar" menu button or Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: "3-bar" menu button or Tools > Add-ons > Appearance
• Do NOT click the "Refresh Firefox" button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes