Troubleshooting HTTP 401 errors in IIS
Is there an index.htm or default.htm under C:\Inetpub\www ?
If not, put one there and see what happens.
(1) Launch inetmgr and right click on site
(2) Go to Properties
(3) Go to Directory Security Tab
If this doesn't work then perhaps
Check on iisstart.asp or localstart.asp, I believe the anonymous auth is disable at file level as well
Uninstall Framework 3.5, 3.0 and 2.0 and reinstalled IIS.
That is becoz IE auto login for you, mozilla won't do that.
So again make sure you enabled anonymous authentication and ensure the resource file can be read by the anonymous account, which is iusr_computername by default.