Windows 7: Can't click on youtube videos (can't toggle volume, can't pause etc)

I've noticed for a month now that sometimes (and this happens like 45% of the time) when I open a youtube video, it does not respond when I try to pause it, play it, toggle the volume button, fast forward by dragging the little dot, expanding the video to full screen). Everything else works, the search bar, clicking on my user name, submit a post, liking a video, clicking on other videos. I'm running on a Windows 7, lenovo, x64 bit. I've tried uninstalling and reinstalling the latest firefox AND adobe flash player. Nothing works -_-. Can anyone possibly help me please? I have noscript, but I allowed all access for youtube. I don't know what is wrong!

Do the same problems occur in IE?

Thank you for your reply. To answer your question, I haven't used IE even though it's on my computer. I will start using IE and see if it does the same. What happens if it does? Why does my firefox have this problem?

Edit-
I've been testing it out the whole day and it works fine on internet explorer (but I'll have to use it some more to see if it changes)

I have also just downloaded google chrome. I will run a trial test to see if youtube does not respond. (Doing pretty well right now though)

Even thought youtube works fantastic on IE, IE is very slow as my default browser -_-

Try reinstalling Firefox 9 again. If problems persist, roll back to Firefox 8.

Mozilla Firefox Web Browser