Session cookies in ie8

I have an aspx application that links onto web wiz forums. It passes asp membership details to the forum in the form of 3 session cookies, email, username and password. The forum reads these and either logs the user into the forum or creatates a new user if they do not exist.
 
All works fine in firefox but not in IE8. The cookies don't get passed.
code behind:
   ' create session cookie to store login credentials
        Response.Cookies("logindata")("Login") = username
        Response.Cookies("logindata")("passw") = password
        Response.Cookies("logindata")("email") = emailad
        Response.Cookies("logindata").Expires = DateTime.Now.AddSeconds(30)

    End ...