full screen?

Hi there I have a small problem my web browser mozilla firefox does'nt let me view full screen to watch videos - it just shows a white screen and I dont know why!

Oh, and since I updated the adobe flash player on internet explorer, that too will no longer allow me to view videos in full screen either!

I have tried tweaking the add-ons and tried to fix this problem but I cannot seem to find an answer so I was hoping that one of you guys might be able to come up with a solution to fix this!

I have also tried uninstalling the flash player and installing the previous version but it doesn't seem to want to install for some weird reason!

If anyone can help with this I would be extremely grateful for your support!

Thank you in advance!