Response.Redirect to current page with cookieless authentication

I have a logon/register control that is on several pages. Users are logged on with code: -
FormsAuthentication.SetAuthCookie(Userid, False)
Response.Redirect(Request.Url.AbsoluteUri) ' Round trip is necessary to complete logon

All this was working OK, except that there was a problem with Internet Explorer users: if their browser had the default privacy setting the authorization cookie was rejected. There was no message, but they were not logged on. See http://forums.asp.net/t/1667895.aspx. To try to solve this problem I changed to cookieless authentication, but now the logon control doesn't work. The problem is that after cookieless authentication the URL changes from
http://localhost:3641/TestGDB/Login_pages/home2.aspx
to
http://localhost:3641/TestGDB/%28F%28EzhVmnfA9A5m-oRZ_hSpdDq_qvnfXM0iUC2dXjeRmUyFAiyskBXuXpx9YXzZBEC7056w5V8MrisSuVFxZFEs76D3UBACz4MTcFK1IZ26VzY3axDu_DN4EVBOWZluYI6czapdB5A0h6TunplULIAX4O9pllE1%29%29/login_ ...