Safari redirects certain URLs to localhost (other browsers are normal)

Hi!

A few days ago I'm having successive connection problems with my Mac.

First, browsing the Internet was ridiculously slow (50, 60kb/s), but all sites opened normal. But I was giving around.

The problem is that now Safari stopped open some important sites (YouTube, Facebook, Twitter - but it opens Google): when I enter the URL, it redirects me to "http:/localhost/". An error message appears, but is because my webserver is offline - and not use it for months, by the way.

The interesting thing is that if I use Mozilla Firefox, the sites are normally open, let alone with the problem of slow.

I checked my hosts file and everything is normal.

Thanks!