Just to follow-up, I did send you the .REG file (on Dec 27), which references HKLM (not HKCU) and doesn't work for me, so there may be a problem to look at there. But for my immediate needs, your comment about not trying to update HKCU from an installer was enough to convince me of the error in my ways, so I've followed your suggestion and moved the necessary registry logic to the application itself. If the email was lost in the holiday shuffle and you still want to look at that, let me know. Otherwise, feel free to assume it's a spurious error on my part and can be dropped, as the matter is strictly academic at this point. Happy new year and thanks for the excellent support.