Check your Apache configuration files. This is where authentication first takes place:
C:\ptc\Windchill_9.0\Apache\conf\extra\app-Windchill-Auth.conf
This file should inculde all of the options to connect to your Corporate AD. Verify that your AuthLDAPURLis correct with your domain\IT administrator. If not, modify it and restart Apache.
Ex.
<authnprovideralias ldap=" windchill-enterpriseldap=">
AuthLDAPURL ldap:ADhost.example.com:3268CN=Users,Dc=example,DC=com?sAMAccountName?sub?(objectClass=*)
AuthLDAPBindDN "CN=Bind User,CN=Users,DC=example,DC=com"