|It could very well be a redirection rootkit.....You need to get rid of it. Google rootkit.|
It could be the site your going to has changed it's address on the web and your being redirected to the right site.
If this is on every site you go to.....bet you have a rootkit (virus)
If just one one site.....wait till it loads, then re bookmark it as the old bookmark is no longer valid.