Can you check your IIS log to see if you have some 401 error?
Can you try this method: http://support.microsoft.com/kb/896861/en-us
Method 1: Specify host names (Preferred method if NTLM authentication is desired)
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To specify the host names that are mapped to the loopback address and can connect to Web sites on your computer, follow these steps:
- Set the DisableStrictNameChecking registry entry to 1. For more information about how to do this, click the following article number to view the article in the Microsoft Knowledge Base:
281308 (http://support.microsoft.com/kb/281308/ ) Connecting to SMB share on a Windows 2000-based computer or a Windows Server 2003-based computer may not work with an alias name
- Click Start, click Run, type regedit, and then click OK.
- In Registry Editor, locate and then click the following registry key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\MSV1_0
- Right-click MSV1_0, point to New, and then click Multi-String Value.
- Type BackConnectionHostNames, and then press ENTER.
- Right-click BackConnectionHostNames, and then click Modify.
- In the Value data box, type the host name or the host names for the sites that are on the local computer, and then click OK.
- Quit Registry Editor, and then restart the IISAdmin service.