I just added this small add-on to my forum, puzo home-made, if you're already logged in you won't be able to access the policy.asp page like you do now, i did this mainly to save bandwidth.
Here's how:
On line 43 in policy.asp after the last include find this:
<!--#INCLUDE FILE="inc_header.asp" -->
<%
And add the following code after it
if strDBNTUserName <> "" then
Response.Write " <table width=""100%"" border=""0"">" & vbNewLine & _
" <tr>" & vbNewLine & _
" <td><font face=""" & strDefaultFontFace & """ size=""" & strDefaultFontSize & """>" & vbNewLine & _
" " & getCurrentIcon(strIconFolderOpen,"","") & " <a href=""default.asp"">All Forums</a><br />" & vbNewLine & _
" " & getCurrentIcon(strIconBar,"","") & getCurrentIcon(strIconFolderOpenTopic,"","") & " Registration</font></td>" & vbNewLine & _
" </tr>" & vbNewLine & _
" </table>" & vbNewLine & _
" <p align=""center""><font face=""" & strDefaultFontFace & """ size=""" & strHeaderFontSize & """ color=""" & strHiLiteFontColor & """>There Was A Problem!</font></p>" & vbNewLine & _
" <p align=""center""><font face=""" & strDefaultFontFace & """ size=""" & strDefaultFontSize & """ color=""" & strHiLiteFontColor & """>You are already registered at our forum</font></p>" & vbNewLine & _
" <p align=""center""><font face=""" & strDefaultFontFace & """ size=""" & strDefaultFontSize & """><a href=""JavaScript:history.go(-1)"">Back to Forum</a></font></p>" & vbNewLine & _
" <br />" & vbNewLine
WriteFooter
Response.End
end if