Windows 10 update - desktop turns black - then recovers - then turns black...

All...

Hope somebody can help me. 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 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