I received this request from Shahid Hussein from Global Investment House.

Dear Ali Reza,
I am trying to install windows share point services 2.0. after the wss installation right after iisreset command, it opens browser and asking for the user name and password. Why it is asking for password.
SQL Server and IIS both services are running fine on that server.
Here is the reply
Dear Shahid
 The reason is very simple. In default installation of WSS the virtual server has disabled Anonymous Access and uses integrated windows authentication.

If you are using Internet Explorer to access the portal site by default IE uses automatic login for the integrated windows authentication from IIS side. Otherwise simply go to IE, tools menu -> Internet Options -> Security (Tab) -> Select the local Intranet and select the custom level. Once you scroll down you will find the user authentication options. Make sure one of the Automatic options is selected. You may need to do the same setting for the trusted sites.

If this does not solve the problem you should check the IIS and make sure that it is configured for Integrated Windows Authentication (not Basic Authentication).
Cheers
Alireza