Guys i had the same problem, i’ve been struggling for 3 days, and i fixed it today!!! what i did is just remove all steinberg programs just kept Cubase 10 installed, that helped open cubase 10!!! and now i started installing the Vsts, etc none gave problems,!!! thy this out!
so basically:
Uninstall all steinberg products but keep Cubase 10
run Cubase 10 , program should open now!
install the rest of the stuffs!
done!!!
good luck
hope it helps ! greetings!