[BruceKahn]

Ben, thanks for taking the time to make a suggestion. Unfortunately, I got the same result.
Albee, yes, at one point before posting I found that Windows had grabbed MOTU as the default audio driver. I corrected that and it did not help. Also already reinstalled MOTU, no help. Just checked Windows for all updates, there were a handful but not the sound card. I'm assuming all is OK with the USB connection because PT is seeing the MOTU, it just won't hold the selection when I choose it. It seems perhaps PT keeps selecting the sound card regardless of what I manually select, and I can't find anything in PT settings that would account for that. Thanks for your suggestions.