SketchUp 2022 on Mac Monterey freezing

When I start up SU 2022 (Monterey on Mac) things seem to work for a while (the orbit/zoom etc. seem slow), but within a minute or so all the buttons become unresponsive. Worse, when I click another window to switch applications, I find that all the applications (including the Finder) are unresponsive. As a result I can’t even do a restart as the Finder menu is also unresponsive – I have to do a hard restart using buttons. When I try to use SU 2021, the same things happen. I have thrown away all the preferences, but they are just regenerated with the same issues.
I have been a long time user of SketchUp and never encountered such a problem previously.
I’d appreciate any suggestions…