Make sure you are not blocking content.

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). Is the problem still there?

Hi,

You tube was fixed in safe mode but as soon as I reload without safe mode selected I have the same problem!

Thanks Elaine

It could be the work of one of your add-ons, or it could be Hardware Acceleration. How to disable Hardware Acceleration {web link}

Type about:addons<enter> in the address bar to open your Add-ons Manager. Hot key; <Control> (Mac=<Command>) <Shift> A)

In the Add-ons Manager, on the left, select Extensions. Disable a few add-ons, then Restart Firefox.

Some added toolbar and anti-virus add-ons are known to cause Firefox issues. Disable All Of them.

If the problem continues, disable some more (restarting FF). Continue until the problem is gone. After, you know what group is causing the issue. Re-enable the last group ONE AT A TIME (restarting FF) until the problem returns.

Once you think you found the problem, disable that and re-enable all the others, then restart again. Let us know who the suspect is, detective.

Hi,

Still not working. It has to be the Firefox browser as my other browser is working fine. Might need to update at your end?

Thanks Elaine

Did you disable all of the add-ons? What about Hardware Acceleration?

Hi,

All good now. It was the Hardware Acceleration, disabled now and working well.

Thanks Elaine

Glad to help. Safe Surfing.