in inc_header around line 350 you will find this code
if (mlev = 0) then
if not(Instr(Request.ServerVariables("Path_Info"), "register.asp") > 0) and _
not(Instr(Request.ServerVariables("Path_Info"), "policy.asp") > 0) and _
not(Instr(Request.ServerVariables("Path_Info"), "pop_profile.asp") > 0) and _
not(Instr(Request.ServerVariables("Path_Info"), "search.asp") > 0) and _
this is the bit of code that stops the logon screen from apearing when on certain pages.