Error 403

Hey there !

I recently had my datebase moved to a 5+ mysql server due to the requirements of the recent wordpress versions. So I used Mysql Administrator to make a db backup. Then upgrading wordpress. Now I get error 403, any ideas? I spoke to my hosting company, they said its a software issue but I am not so sure as the error includes something like “this webpage needs you to logon”.

I am lost in space, heeelp ??