Certain Authenticated Sharepoint Users Get Access Denied Error

Whenever we add our Active Directory groups in the Sharepoint site groups, some of the group members receive the Access Denied message. This is a problem we have to face in Sharepoint 2007 and it doesn't resolve even after adding members of the group individually. So, to get rid of this problem, adhere to the following steps:

• Add users in the DomainName/UserName format, instead of using just the UserName. Avoid adding AD groups directly
• If you have hosted your site on port 80, and have used a different name apart from the machine name as http://ABC, then in this case, don't forget to make an entry of your site in the Alternate Access Path, under the operations tab in the central administration.