Email anomaly

Wondering if anyone has experienced this before. I have code that calls the OpenNewMessage function from mail codeunit (397). On my system the code works great – correctly opens an Outlook new message window. On the customer’s system, the new message window opens when the code is called but the user must use the (Shift + Tab) key combination twice + Enter once to display the contact list. The mouse is rendered useless on their system until they use the above key combination to display the “select recipient” dialog. Testing on my PC has included using the customer’s license, logged in as several different users (variety of permissions including super). Also of interest – Customer is able to use the standard email functionality (icon on customer card) without incurring the above issue. Customer does not have OCX or CFront granules (1750 and 1800 - I would hate to sell them the granules only to have the problem persist).