Driver stopped working .. helpppp pls i'v tried everything

Hello,
I have this problem that my graphics card stops responding when playing youtube videos sometimes the screen totally resets and I have to reboot and sometimes the screen goes black and it gives me the msg that the driver stopped responding and now its recovered, I dont have any problems playing games .. heavy ones like NFS or Assassins creed! just the youtube! I'v read many articles on the internet like trying another versions of flash player or changing or updating the vega driver but nothing is working!
My system configurations is
Windows 7 64X
Core 2 quad 2.4
Xfx 9800 Gtx+
4 gega Ram
Gegabyte EP 45 motherboard

Pls If anybody know any solution for such a problem help pls.
Thx alot.