Won't switch audio engines

[BruceKahn]

PT decided to default to my sound card. When booting up, reaches "initializing audio engine", I get a message that it can't initialize the audio engine. Click OK, switch to MOTU interface, click OK, startup screen returns to "initializing audio engine". After a few seconds I get the same message, when I click OK I see that it is still on my sound card, switch to MOTU, click OK, around and around and around. Switching to MOTU and hitting OK seems to take, but doesn't. Just keeps returning to internal computer sound card and will not stay with MOTU interface. This is after two years of running with Windows 10 and MOTU LP32.
Anyone?