We had an issue recently when setting up CRM 2011 IFD up. The issue was that internally we were unable to access the CRM website as it kept throwing a Windows Authentication box prompt up from our ADFS server. Then we eventually we got a 401.1 error after failing to authenticate 3 times.
We checked all IIS setting and ADFS configuration on the ADFS server and all of it was fine.
The issue turned out to be Loopback checking.
- Click Start, click Run, type regedit, and then click OK.
- In Registry Editor, locate and then click the following registry key: HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlLsa
- Right-click Lsa, point to New, and then click DWORD Value.
- Type DisableLoopbackCheck, and then press ENTER.
- Right-click DisableLoopbackCheck, and then click Modify.
- In the Value data box, type 1, and then click OK.
- Quit Registry Editor, and then restart your computer.
As soon as we added this setting and rebooted server everything sprung into life and started working