Zoom problems on Mac with 10.15 Catalina

I have read several discussions about problems caused by running Zoom on Macs, but most of them involve crashing or freezing. Mine is (I think) a little different. During Zoom meetings, I frequently lose the picture and my screen goes all black on one side and all white or gray on the other. It stays that way until I force restart my Mac (command-control-power), and then the Mac takes 5-10 minutes to restart. When I finally get it up and running and restart Zoom, I'm told by the Zoom client that I can't rejoin the meeting I was in because the host is in another meeting (although I think this last part is a Zoom problem and not a Mac issue).

Any ideas would be appreciated!