update your flash.....
that might help
http://www.adobe.com/shockwave/downl...ShockwaveFlash
ik
edit:
sorry just noticed you did.
you got Firefox?
if so use firefox to update it, then reboot firefox, I had that prob a while back in an old version of FF
you read this?
http://www.google.com/support/youtub...15&topic=10560
1: download
this
2: close browser & run that program
3: reboot your computer
4: download
this
5: close browsers and install said flash prog
6: open browser
7: test on you tube