Long version (I tried for 8 months : OCCD test on drives and ram; change GC, reinstall windows 3 times (11 and 10) reinstall all nuendo / kontakt several times; chaged HD; used session and path names without special caracters and short; tried those sessions on my old computer; .. always the crash. Probably 20mail exchange with steinberg support, they say it's kontakt causing the problem and same exchange with NI (NI is still on it but I had to pause for holiday)