Version 16.1.1 (49141) Model Name: iMac Model Identifier: iMac15,1 Processor Name: Quad-Core Intel Core i7 Processor Speed: 4 GHz Number of Processors: 1 Total Number of Cores: 4 L2 Cache (per Core): 256 KB L3 Cache: 8 MB Hyper-Threading Technology: Enabled Memory: 32 GB Boot ROM Version: 22.214.171.124.0 SMC Version (system): 2.23f11 Note: I have two external Thunderbolt displays. With windows 10 Pro 1909 build 18363.1198 Since upgrading to the latest Parallels version this and similar windows VM's all periodically freeze for periods of between 5 and 15 seconds. I'm seeing this at least 70 times a day. During this time windows can sometimes appear black - particularly noticeable with Visual Studio During the freeze everything running in the VM appears to be suspended. With the VM not in full screen mode the CPU usage indicator drop down does not indicate that any particular app is using excessive CPU rather it appears to be the parallels host process itself which is somehow stalling the VM. The VM has been allocated sufficient RAM and CPU resources and does not reach limits where it is swapping or otherwise performing badly. I hesitated before reporting this so I could eliminate all other possible causes first but I'm now confident that this is an issue with the Parallels host. This issue happens a lot while running visual studio and while it is true that VS can sometimes use excessive CPU the issue is not only observed while running VS and can occur while very few programs are running. During the freeze the machine is completely unresponsive and even Task Manager stops updating! However the CPU usage indicator drop down on the title bar of the (non-fullscreen) VM seems to show CPU usage 0 and reports "No apps using significant CPU" at the time of the freeze. There are indications that the freeze occurs during certain disk I/O operations but this is the only possible clue I have. Could it be related to the earlier "XCOPY" related issue I reported previously - which was fixed in build 49141? This is a rather annoying issue. I note a few similar reports from others. Also I was trying to open a new ticket but this is taking me round and round in circles and I can't seem to open a new ticket - issue with website or the fact that I still have one open ticket.