You receive a "Can't contact LDAP Directory server (81)" error message when you open the Address Book in Outlook
This issue may occur if an address book that uses Internet directory services (LDAP) is configured in Microsoft Outlook, and Outlook cannot contact the LDAP server that is configured for that LDAP address book.

For Outlook 2007
If you are not using Lightweight Directory Access Protocol (LDAP) Internet directory services, remove the LDAP address book. To do this, follow these steps:
Start Outlook.
On the Tools menu, click Account Settings.
On the Address Books tab, click the LDAP address book that you want to remove, and then click Remove.
Click Close.
Exit and restart Outlook.
If you are using Lightweight Directory Access Protocol (LDAP) Internet directory services, make sure that the settings for the LDAP address book are configured correctly. To do this, follow these steps:
Start Outlook.
On the Tools menu, click Account Settings.
On the Address Books tab, click the LDAP address book that you want to configure, and then click Change.
Verify that the settings for the LDAP server are correct.
Click Next, and then click Close.

For Outlook 2002 and 2003
If you are not using Internet directory services (LDAP), remove the LDAP address book. To do so:
Start Outlook (if it is not already started).
On the Tools menu, click E-mail Accounts.
Under Directory, click View or change existing directories or address books, and then click Next.
Under Directories and Address Books box, click the LDAP address book that you want to remove, and then click Remove.
Click Finish.
Quit, and then restart Outlook.
If you are using Internet directory services (LDAP), make sure that the settings for the LDAP address book are configured correctly. To do so:
Start Outlook (if it is not already started).
On the Tools menu, click E-mail Accounts.
Under Directory, click View or change existing directories or address books, and then click Next.
Under Directories and Address Books box, click the LDAP address book that you want to configure, and then click Change.
Verify that the settings for the LDAP server are correct. Click Next, and then click Finish.
Hope this work!