Can you give me more information about the Outllok version you're currently using. Moreover, when you say that you open the address book, do you mean opening it in the same Outlook window or in a new window?

Can you give me a set of instructions (click here, do that, ...) so I can make tests and corrections?

Well, I cannot reproduce the problem.

Can you try this; run the registry editor (regedit.exe), go to the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\R2d2KernelAuthority\Parameters key and edit the _NeverSubClassPrograms value. Add *\Outlook.exe to its content and try again.