Safari doesn't play vimeo videos!?

Yesterday, my favorite web browser Safari stopped playing videos in vimeo. Videos just don't load anymore. Youtube and other sites work, but not vimeo. I've tried to use internet explorer, and what a surprise, all videos play. So I am sure that the problem is in Safari.
I have reset safari, re-installed safari and reinstalled my flash player. But still nothing. And even that's not all. It loads some websites much longer than IE or another browser. Why?

What should I do ?

I use windows 7, Safari 5