Install the Media Feature Pack if applicable.

That pack is for windows N editions, I am not running N.

I just tried troubleshooting mode and the problem goes away when in that mode. This means that it is probably one of my extensions that is the problem

This also doesnt make sense because I have it set so that all firefoxs settings (incl bookmarks, addons, etc) are synchronized across all devices.

How would I go about trying to find out which addon is producing the problem?

Does it still happen if you disable hardware acceleration then restart the browser?