securing PDF files (among others)

[JAG]

I am using the Treeview webcontrol on a .aspx page to display files
that are in a specified subdirectory off of wwwroot. I have
implemented Forms Authentication, and currently the user must accept
the disclaimer prior to being redirected to the Treeview webcontrol
page.

I am ultimately wanting to show the disclaimer page each time the page
containing the Treeview webcontrol is requested. For example, if a
file is accessed directly from the URL of the file (subdirectory) they
are redirected to the disclaimer page, and after accepting are sent
the originally requested file.

I've got this working to the point that if the Treeview page is
accessed directly, the disclaimer page displays where you must accept
before continuing. I can't get the redirect when a file from the
Treeview webcontrol is directly requested by URL. Right now the file
is served as requested.

I tried mapping the file extension to ASP.NET ISAPI DLL in IIS but
that didn't make a difference. I also tried adding a separate
web.config (which simply had my authorization block) to the
subdirectory and that didn't work.

Am I missing something obvious here, or am I asking too much from
Forms Authentication? Is there no solution to this problem?

Thanks.