As you are requiring visitors to login before seeing the forum, you have two choices.
1. You change the option that requires visitors to login to off, or...
2. You have to create a new inc_header.asp for your non-forum homepage, which doesn't require visitors to login.
If you want to go with #2, you must remove the following code from your new inc_header.asp:
if strRequireReg = "1" and strDBNTUserName = "" then
if not Instr(strScriptName,"policy.asp") > 0 and _
not Instr(strScriptName,"register.asp") > 0 and _
not Instr(strScriptName,"password.asp") > 0 and _
not Instr(strScriptName,"faq.asp") > 0 and _
not Instr(strScriptName,"login.asp") > 0 then
scriptname = split(request.servervariables("SCRIPT_NAME"),"/")
if Request.QueryString <> "" then
Response.Redirect("login.asp?target=" & lcase(scriptname(ubound(scriptname))) & "?" & Request.QueryString)
else
Response.Redirect("login.asp?target=" & lcase(scriptname(ubound(scriptname))))
end if
end if
end if