Thanks, all.  Joined the forum out of desperation with the "dreaded loop" which is still not conquered.  Had a similar problem going from S9 to S11.  Did NOT remove S9.  With S12, removed S9 and S11U (I read the KnowledgeBase, too).

AVID/PINNACLE has a good product, but their installation programs leave about 98% to be desired.

Sorry, had to vent.  I'll be nicer next time.