Strange Issue with tags wp 2.5

Hi sorry my english.

I have updated to the recent version of wp, the 2.5, I believe that it is an error of the browser. When I write in the area to add tags, the page changes aiming at host where i am hosted. The error happens just at the moment at appears the box show me some tags already existing. With firefox this happens to me, with Opera does not add tags to me.