Myself and my boss use Parallels on our MacBook Pro's to run Windows 10, and both of us have had the same problem for 6 months or more, but not always at the same time. The problem is that after Windows runs an update (not every time, just sometimes), and then reboots, we get the spinning color wheel in Mac, and both Parallels and Mac becomes unresponsive. The only way to get out of it is to hard reboot the Mac, sometimes 3 or 4 times or more, taking from an hour up to so far today 4 hours of doing this before the Mac becomes responsive again and the computer can be used again and Windows boots in. When this has happened to mine I have been able to boot in safe mode into Mac OS, but trying to start Parallels ends up with the same result. I recall once when mine was doing this I left it sitting overnight and by morning it had apparently finished whatever it was stuck on. On my boss's machine he's had this happen at least once or twice a week for the past month or so and he's fed up and ready to switch to something else if we can't get something fixed with it. Personally I haven't had the problem on my Mac in a couple of months or so, and both of us update Windows regularly. We both use Mac OS Catalina (latest version) and he is using Parallels 15, I have Parallels 14, both updated regularly. Upgrading to 15 didn't fix anything for him and installing recent updates for Parallels hasn't worked either, so I didn't bother to upgrade mine from 14. We have done the First Aid in Mac Disk Utility with no effect, and checked both computers for hardware issues and there are none. I know others have had this issue but I haven't found any solves for it online, any help is appreciated as we are ready to throw in the towel for Parallels.