I ran into an interesting issue setting up SQL Reporting Services 2008 R2 using a host header, i.e. SSRS.MyCompany.com.
When I would attempt to access the SSRS Report Manager using http://ssrs.mycompany.com/reports, I would get a 401 Not Authorized Error.
I ended up having to make two registry changes in order to get it to load properly.
*** DISCLAIMER: I don’t recommend that you make any changes to your registry unless you are familiar with this tool and have a disaster plan in place to repair it in case you run into any issues. ***
Having said that, here’s what I did:
  1. Type RUN -> REGEDIT to get to the Registry Editor
  2. Traverse HKEY_LOCAL_MACHINE -> SYSTEM -> CurrentControlSet -> Control -> Lsa -> MSV1_0
  3. Right-click on MSV1_0 and choose NEW -> DWORD, call it DisableLoopbackCheck, and set its value to 1.
  1. Right-click on MSV1_0 and choose NEW -> Multi-String, call it BackConnectionHostNames, and set its value to your host header, which in my case is SSRS.MyCompany.com