Great problems with Safari 6.0.

Hello guys, recently I have two great problems with Safari 6.0.

1) Sometime when I'm on YouTube and I try to load a new video, Safari can't do it because appear this:

This is really REALLY annoying because 1 video of 3 I have this kind of problem.

Is a problem with Flash Player? I tried to unistall/install it but nothing change.

2) Sometime when I load a new page or write something (like now) seems like text/page disappeard or freeze.

Here few screen for help you to understand.

Above a screen where I'm chatting on Facebook and text freeze/disappeard

Below a page with a little freeze on Twitter (but this happens on every site even in larger dimension).

With Firefox i haven't this kind of problem, everything is ok, but i prefer Safari because is lighter and faster IMHO.

Hope you can help me.

Bye!

PS: Sorry for my bad english I'm Italian. :-)