I keep getting this message:
...and for the life of me I cannot figure out what program might be trying to access my email address information - any ideas for getting rid of this message or tracking down the offending program?
Most probably there is a COM add-in of a product you installed, which can be disabled through Outlook Security Settings template.
Try to run Outlook in safe mode and see if it still happens - to do so type in the Run window
To disable COM add-ins go to File | Options | Add-ins and click on the Go... button
Here, try to disable these add-ins one by one and see who is the one that is actually causing the problem.