Okay guys, so I reinstalled Cubase one more time and really manually made sure, that there’s no folder & file related to Cubase left on the computer. Again same problem.
Then I tried pulling some plugs in terms of my usb devices and suddenly Cubase started again!
To keep the long story short, I’ve found the one thing, that caused the problem: I have an active usb hub connected to my computer (where the dongles are attached, plus my logitech keyboard and mouse) and it seems like the computer doesn’t like it to be put in to an usb 3.0 port. After I put it into an usb 2.0 port, everything was fine again.
I remember pulling it off and putting it back in - not caring about the 2.0/3.0. So it must’ve been in a 2.0 port all the time before.
Weird, but that was it!
Thanks so much for helping, guys!!! <3