All... I hope somebody can hep me. I also posted the below to the windows forum. Have had a load of folks read but no replies/solutions... so thought I would try a different forum just in case. Here is my configuration: MAC Mini - 16Gb memory - 2.5Ghz core I% OSX 10.9.5/Mavericks External HD display connected by MAC/Display port to VGA adapter Parallels 11.1.1 (32312) Windows 8.1 VM Windows 10 VM I have updated a previously working Windows 10 with a couple of windows updates. The first update completed successfully and all was well with the world. The second (latest windows-10 update) appeared to update successfully. The RESTART completed (took about 2 hours to get to 100%). The VM then appeared to boot properly and desktop displayed with the usual blue background. Then after about 3 seconds, the VM window turned completely black. Then recovered to the usual desktop after about 2 seconds... then turned black... then recovered etc. And the cycle continues. It is almost impossible to get any response (even trying to SHUTDOWN or RESTART) before it goes black and freezes me out. Within the parallels desktop control centre, I selected the COG and checked the following: - CPU & MEMORY : was set to 2xCPU + 1Gb memory : I changed this to 2xCPU + 4Gb memory (on the basis that I have 16Gb in the MAC and my windows-10 is the 32 bit version) - GRAPHICS MEMORY : was set to 256Mb : I changed this to 512Mb Rebooted the VM - same issue. Forced a RESTART - same issue Killed Parallels control centre and restarted - same issue. Another VM I have (recently updated with latest Windows 8.1 updates) continues to boot just fine and works just fine. I have searched the windows forum and can see stuff about FLICKERING displays, but that is not the problem I have. I note that there is a PARALLELS 11.2.3 update available. Have had a quick scan of the bug fixes and cant see anything which seems like it would be the fix. Any help or advice would be very much appreciated. I probably don't do the windows-10 updates nearly frequently enough. I hate the windows-10 update process as there appears to be no control over when it runs. It does kindly warn me it may impact performance when downloading and installing... but it effectively makes the MAC unusable. CPU utilisation is anything between 40% to 200% continuously (mostly > 100%) and the latest major update took 4 hours to download and install. The RESTART/configuration of the update took another 3 hours (I get about 13Mb/sec throughput on my ADSL). I must admit I use Windows 8.1 most of the time - when I have to use windows, just because the updates don't effectively stop me from using the computer as they are user schedulable. APOLOGIES TO ALL - RANT OVER NOW
I just started to have the exact same problem. Was this ever resolved? Started to occur after update to PArallels 16 and regular Windows 10 update.
This exact same problem began shortly after installing latest Parallels upgrade to V19 and updated Toolbox. Scenario is VM starts okay and then after prompt and sign in using Microsoft PIN the Win 11 Desktop flashes alternately between black wallpaper and the desktop image. Have tried restart, Re-boot, and complete reinstall of PLLS-V19 and Toolbox without any resolution to the problem. The forum contains reports of similar behavior going back a few years yet no cause or fix appears. Thank you in advance for any suggestions or guidance on how to diagnose and resolve this problem.
