Thanks Jackie. I think I may have been a bit imprecise about the nature of my problem. Those scansoft voices appeared yesterday in my Calibre viewer's "Configure Read Aloud" list of voices. They were not showing up in my Calibre list when I posted
these screenshots two days ago, then they appeared, and I stupidly selected one. The error message I posted above is 100% accurate, because a regedit search shows no entries in any key in the entire registry for any ScanSoft voices. My problem is that I can't access the Calibre viewer's "Configure Read Aloud" dialog to repalce the missing voice with one I do have, because attempting to do so by clicking the gears icon brings up that error message.