HTML5 full screen issue

Hello everyone!

So I'm hoping this is the right section of the forum for this issue:

I can watch every single HTML5 video without any trouble
When I max the video to full screen, it's played in fullscreen without any problems
However when I try closing fullscreen again, the fullscreen image just moves 1mm to the right and freezes.
Only way to quit is by closing the browser via Task manager
This happens in Firefox, Opera, Vivaldi and Internet Explorer, not in Chrome. In Chrome everything works as it's supposed to.
But since I really dislike chrome and have really fallen in love with Vivaldi lately I was wondering if there's a solution to this issue?
Reinstalling the browser and windows (7 Pro) did not make a difference

I run a phantom II 955 CPU
An Asus M87-TD Evo MB
And a MSI R6850 PE

I really dont know if it's software or hardware related...
Maybe some helpful soul knows a solution ?
 
Solution
it use different engine to render html5 tag, some might use hardware, some might not.
gpu driver.
I'm still running windows 7 with and old AMD gpu too. no issue on youtube full screen on firefox.
so it work fine in chrome, what other browser did you try?
I said if it work fine on another browser . the issue is with vivaldi, if it doesn't work in any browser, it hardware related, since it work with at least 1 browser , it not hardware.