ColdFusion gives a 401 when using Windows Authentication

I have a Windows 2012R2 server running CF 11.  ColdFusion is running as a local service account, and is working properly for all other applications on this web server.

I am migrating an old app over from ColdFusion 8 that requires Windows Authentication.  When using Anonymous access, the users can access the app and it works properly.  When I turn on Windows Authentication, users are getting a 401 error.  Event Viewer shows a successful logon (4624).  If they access "file.cfm", they get a 401 error.  If they access "file.txt", they get the contents of the file successfully.  Authentication is successful, apparently, and both files have the same permissions. 

When the user is made a local Administrator, he is able to access the file.  Taking away Administrator privileges, we get the 401.  I tried giving that user full control over webroot, over CF.root, over everything I could think of, but no luck. 

I tried using ProcMon to point me somewhere, but must not know it well enough to get anything I can use here.  No Access Denied.  What else can I do? Any ideas?

Thanks...