When I try to install HP3, the installer shows that no ZfD is installed
on the server - ZfD 7 SP1 recognizes the previous install. Is this a
problem with the ZfD Server Registry keys?

Also, the Install again reports errors - as the installer did with
6.50, 6.51 and 6.52.

If there would be a working reg key file I could check with, this would
be a good point to start.