Some users cannot access Exchange Server 2007 OWA

To resolve this problem, follow these steps:

1. Open Active Directory Users and Computers.
2. Click View, and then click Advanced Features.

Note To make the Security tab available at both the user level and the organizational unit level, you must enable the Advanced Features option in Active Directory Users and Computers. This option is available under the View menu.
3. Open the properties for both the user level and the organizational unit level that the users are located in, and then locate the Security tab.
4. Click Advanced.
5. Make sure that the following check box is selected:
Allow inheritable permissions from the parent to propagate to this object and all child objects. Include these with entries explicitly defined here.
6. Force Active Directory replication.