I'm running Windows 10 (1903) in Parallels 15 (15.1.3) on macOS Catalina (10.15.3). Every so often, Windows 10 and the Parallels app will completely freeze, and macOS will simultaneously grind to a halt. When this happens, there's nothing I can do to try to unfreeze things - Windows won't respond to any input at all, and anything I try to do on the macOS side (like launch Activity Monitor to see what's going on) will just give me a spinning beachball or crash. I just have to sit there and wait, and eventually it'll clear up and start working again (until the next time it freezes, whenever that is). When it freezes, the freeze can last for anywhere from 1-2 minutes to upwards of a half hour! And it doesn't seem to matter which apps or resources are being used in either macOS or Windows; I've had it freeze while sitting at the Windows desktop with no apps open, and I've had it freeze even if Parallels is the only Mac app running. The VM is stored on my Mac's internal SSD (with ~100 GB of free space), and I have 16 GB of RAM, so I'm not short on resources. I've tried doing "restore defaults" in the Windows VM's settings to make sure I'm running it with the optimal CPU/RAM settings, and I've tried both the Parallels hypervisor and the Apple one, but nothing's made any difference. I'm tempted to say this is an issue specific to Catalina, as I didn't notice it on Mojave, but I upgraded to Catalina months ago and the freezing only started more recently (within the last few weeks). I pay for the Parallels subscription, but I'm going to cancel it and switch to Fusion if I can't get this resolved. I'm running the latest versions of Windows, Parallels, and macOS, so I expect this to be a supported configuration that should work without issue. Having my VM freeze for 30+ minutes with no warning is unacceptable!