After adding the registry variable I still don't get the dialog box opening up. I have the earth icon on the desktop, but clicking it does nothing (other than show graphically that the button was pushed).

I'm using ArcMAP 9.0, but there is a warning as the program starts that the ArcSCAN extension has expired.

Also, the button appears to have a small notch in the upper left-hand corner. Maybe that tells you something more than it tells me.