After fixing the previous issue with host headers and NTLM authentication, we discovered that we could only login to the site from the server itself. From every other machine we received the following error message when authenticating:
at Microsoft.CommerceServer.Interop.Profiles.ProfileServiceClass.GetProfileByKey(String bstrKeyMemberName, Object sValue, String bstrType, Boolean bReturnError)
at Microsoft.CommerceServer.Runtime.Profiles.Profile..ctor(ProfileContext profileService, String keyName, String keyValue, String profileType)
After many hours of grueling troubleshooting and reloading the site from scratch, I came across the following Microsoft hotfix: http://support.microsoft.com/kb/975603
After applying the hotfix and following the directions in the “Situation 2” section, the site started allowing logins.