Did anything weird happen to IIS 6.0 while I was out on vacation?

I have a script that processes a small chunk of code, basically expiring some session variables, the code then uses the HTTP_REFERER server variable to return the user to the page they came from. When I use the script, (which used to work) It gives me an error.
The error is an ASP error telling me that the redirect is empty.

The script look something like this...

(Whereto is a session variable that works, it redirects specifically when needed)

DIM wherefrom
If Session("Whereto" ="" Then
wherefrom = Request.ServerVariables("HTTP_REFERER"
Response.Redirect(wherefrom)
Else
whereto = Session("Whereto"
Response.Redirect(whereto)
End If


Carolus Holman