As a SharePoint developer, I find that I spend a lot of time using one of the Server Operating Systems (2003/2008). Interestingly enough a registry tweak is needed before you can actully do any real testing (like using host headers).
The solution for me and one of my colleagues turns out to be this old known issue
http://wcornwill.wordpress.com/2006/06/06/mapping-host-headers-causes-looping-windows-authentication/
and
http://www.sharepointblogs.com/george/archive/2009/04/16/error-401-connecting-to-local-iis-website-after-3-credential-prompts.aspx
I would only recommend to disable the Loopback checking for developing environments.
Disable Loopback Checking
- open regedit
- Find HKLMSystemCurrentControlSetControlLsa
- Create a new DWORD value called DisableLoopbackCheck and give it a value of 1
- Restart the computer
Or view Powershell
PowerShell
New-ItemProperty HKLM:SystemCurrentControlSetControlLsa -Name "DisableLoopbackCheck" -Value "1" -PropertyType dword