Background

Windows Server 2003 / 2008 domain
Windows Server Active Directory Forest Schema upgraded to Server 2008
Member or DC Windows 2003 Servers with Exchange 2003 Management Tools installed

Problem

Active Directory Users and Computers MMC crashes on Windows Server 2003 machines with Exchange 2003 Management Tools installed. Crash normally occurs after opening a second AD object in Active Directory Users and Computers MMC.

Following Crash Error is displayed:

Microsoft Active Directory – Exchange Extension has encountered a problem and needs to close. We are sorry for the inconvenience.

Cause

Reasons are explained in MS KB946459 article. It does not mention Exchange, but in my case the issue only occurred on servers with MS Exchange 2003 Management Tools installed.

Solution

Microsoft provides a hotfix which resolves this particular issue. You can request hotfix directly from Microsoft KB946459.

Alternatively you can download it from here.

WARNING: This hotfix resolved the problem and hasn’t caused any issues in my particular case. But install it at your own risk!

Microsoft warning:
This hotfix has not undergone full testing. Therefore, it is intended only for systems or computers that are experiencing the exact problem that is described in the one or more Microsoft Knowledge Base articles…
Do not deploy a hotfix in a production environment without first testing the hotfix.
Back up the system or the computer that will receive the hotfix before you install the hotfix.