Thanks for the replies .

I had tried to add alias for my computername/site but its doesnt solve the problem and my site is not set to windows authentication. As for IIS settings , what settings do i need to change to solve the problem? any suggestions ? thanks =)

In IIS, go to the "Directory Security" tab for the application in question and then go into the Anonymous access and authentication control.  Assuming you want anybody to be able to browse to it immediately, Anonymous Access must be checked.  That should suffice enough to let somebody in to the site.  Next, you will need to check any firewall that may exist on that computer and ensure that HTTP is not being blocked (port 80, default).

In our intranet at work, I have Anonymous access disabled with Integrated Windows Authentication enabled -- the reason I do that is I want to know the windows login for everybody coming in because I perform some logic based on that.

Where your site is asking for a username/password combo, however, that sounds exactly like they are not allowed to access your site either because anonymous access isn't allowed, or because the domain security doesn't allow them.

Anonymous access is the default in IIS when creating a new virtual directory.