Cannot log in to Windows Auth protected pages while on the server

Solution 1:

This is caused by the loopbackcheck which is enabled by default starting in Windows Server 2003 SP1. Basically it does an extra check and blocks your Windows Auth request from working on the same (loopback) machine.

You can turn it off by following the instructions in this KB article: http://support.microsoft.com/kb/896861.

Contrary to what the doc says, you don't need to reboot for IE to notice. It will work immediately. Here are the instructions that you can follow (the same as in the KB article)

1. Click Start, type regedit, and then click OK.
2. In Registry Editor, locate and select the following registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa
3. Right-click Lsa, point to New, and then click DWORD Value.
4. Type DisableLoopbackCheck, and then press ENTER.
5. Right-click DisableLoopbackCheck, and then click Modify.
6. In the Value data box, type 1, and then click OK.

Test your page again on the local machine. It should work for you at this point.