I was recently setting up a new virtual test box for SharePoint to work on developing a new project and was trying to mimic my production network with sever and site collection names, however I was getting a prompt to enter my username and password but even entering my credentials I was still not able to access my site. My dev server name was SP2010-SP which is where my central admin site was as well as my first site collection, even this site was giving me issues with login, to make it more interesting I created 2 additional sites at dashboard.company.com and portal.company.com using host headers so I could use port 80. The solution that worked was to do the following:

Specify host names (Preferred method if NTLM authentication is desired)
To specify the host names that are mapped to the loopback address and can connect to Web sites on your computer, follow these steps:

1. Set the DisableStrictNameCheckingregistry 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
2. Click Start, click Run, type regedit, and then click OK.
3. In Registry Editor, locate and then click the following registry key:
   
   

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\MSV1_0
4. Right-click MSV1_0, point to New, and then click Multi-String Value.
5. Type BackConnectionHostNames, and then press ENTER.
6. Right-click BackConnectionHostNames, and then click Modify.
7. 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.
8. Quit Registry Editor, and then restart the IISAdmin service.