Parallels freeze my Mac

[LucaT2]

The problem is low frequency, about once every 1-2 months.
I work with a virtual machine Windows 10 (before it was Windows 7 but I still had the problem) on an iMac with Sierra (10.12).
It happens that working, the mouse pointer disappears and the keyboard no longer responds, even disconnecting and reconnecting them.
In the background, in the Mac, I always run Youtube (on Safari) with a music playlist. When the problem happens, I continue to heard the music for a couple of minutes, after which silence, the pc is completely frozen.
At that point, the only solution is to force the shutdown by keeping the power button pressed for a long time (10 seconds).
The problem is not Windows 10, because before I used Windows 7 and I had the same problem.

Usually, I assign to Parallels 3 of the 4 CPU cores and 6 of the 8 gigabytes of RAM.

Ideas? Tips ?

 

[ParallelsU130]

I don't know why your keyboard and mouse disconnect, but one thing I would say is this:
You are allocating way too much of your CPU & RAM to the VM - so when you have a problem with the VM it is leaving your Mac with insufficient resources to run Sierra. 10.12 needs the full 8GB RAM to run efficiently, and more than one Core. I would recommend that you double your RAM to 16GB and maybe allocate only 2 cores of CPU to the VM? The fact that you had the same problem with W7 tells me that this is causing the problem on the host side.

As a clue, keep the Activity Monitor window open permanently (Applications / Utilities) and keep half an eye on the CPU and Memory usage tabs, and the Memory Pressure situation (bottom), which should normally show a green graph.