Weird Nuendo Bug freezing system and CPU Overload later

my Nuendo problem drives me simply mental.
I work on a lot of projects and sometimes without any issues on very big projects.
The problem seems only to appear if I use several Kontakt libraries. First of all it’ s not only heavly hungry libraries that cause errors. Some work without problems for the whole day and some work fine but only snap at a certain moment.
I did tons of tweaking, checking my ssd drive, deinstalled background services and deinstalled antivirus protection. Exchanged my Nvidia graphics card to a Sapphire. Dropped the 32bit Plugin folder and more… Computer is offline. All drivers and software up to date. Bios Update etc.

The problem is that if the problem appears once in a project I can do whatever I want (render in place) delete instance etc. but it keeps freezing at a certain but random position. It fails to operate on very simple tasks, so it is not when there’s an overload of voices or something like that. Then it freezes. After 20 seconds the cpu meter suddenly goes in the red. I only can reset computer to have it working again properly.
The main problem is, that if this error appears once, it seems to stay in the project and backing it up, rendering tracks doesn’ t make a difference… I also don’ t use too many plugns, except the UAD stuff (latest update)

Recording doesn’ t work, becuase of the freeze, Rendering doesn’ t work either.

I work with resource problems all my life, but this is completely insane. I didn’ t have such kind of issues on my older computers and it is realy frustrating. I would avoid Kontakt, if it wasn’ t a sort of standard for so many libraries.

I use Windows 10 with the latest Nuendo Update. Tried Rme Fireface UCX with Fireface and USB (same problem).
Tried various Firewire connections. Did project backups nothing makes the problem disappear…

Thanks for advice.