Give access to non virtual folder through configuration entry? ERROR: path attribute must be a relative virtual path. It cannot contain any of '?' ':' '\' '*' '"' '<' '>' or '|'.

I have a webpage running under a virtual directory that is mapped to d:/webapplication that produces an excel spreadsheet, the page calls a library object that generates a report and places it in a folder d:/attachments. This folder is not in the virtual directory. When I access the webpage i click a button and it attemps to return the created spreadsheet as a mim content type application/vnd.ms-excel.

However i getting redirected back to the login page of the application. Ive also noticed that the excel spreadsheet has not even been created at this location. So assuming this was an authoriseation problem (i.e. I was not authorised to get access to the d:/attachments folder from the web client) I add ...