If you are unable to log in as an Active Directory user after installing, check the following:
Correct any errors reported by the status command, then try logging in again.
vastool user checklogin <username>
The output displays whether the user is a known Active Directory user. If not, you may need to map the user to an Active Directory account or Unix-enable the Active Directory account. If the user is known, an access control rule may prevent them from logging in. The output of the command displays which access control rules are in effect for the user.
You may need to restart window managers such as gdm in order for the window manager to reload NSS modules. Until the window manager reloads the NSS configuration, you will be unable to log in with an Active Directory user. Other services such as cron may also be affected by NSS changes. If you are unsure which services need to be reloaded, reboot the system.
If you are configuring Authentication Services on VMware ESX Server vSphere (ESX 4.0) the reason you can not log in may be related to access control issues. Please refer to Configuring Access Control on ESX 4 in the Authentication Services Administration Guide.