Outlook security message – need help asa

My boss is using Act with Outlook 2000. He has messed with his Outlook security settings. When he sends a message from Act he gets the following “A program is trying to access an email address you have stored in Outlook. Do you want to allow this”. We can’t find where the message is coming from. We tried resetting all the security settings back to default but the message is still there. It’s driving him crazy. Can anyone shed light on which settings need to change?