I am facing problem with the session variables.

I have a login page in my website. Which sets a session variale (Session("username")=form.username) at the time of login.

In signout page I have this code. Session("username")="".

In my other page first I check whether a user is logged in or not by checking variable Session variable. Code is:

Code:
If Session("username")="" then
Response.Redirect("login.asp")
End If
If user is already logged in s/he will be directed to his selected page.

My problem is even if the user has signout and if he tries to access protected first time just after signout he sees the page and previous used username is shown as logged in. But if the page is refreshed once, he is directed to login page, means even after signout the session variable still holds last logged in username name, but once the page is refreshed it clears the session variable and direct the user to login page.


Can any one tell me where is the problem?


Thanks