Thanks, Nat.
Your last suggestion seems te be relevant.
I excluded AVS from viruscontrol (F-secure) - repair-tool had already been done, few days ago, after googling the problem.
Now trying to repair again (following your suggestion), the repair-tool itself gave an Access violation message, twice. Still I managed to activate the tool afterwards: no errors, all repaired smoothly.
Then trying to run one of the AVS-applications, I got the same message again: Access violation, twice, followed by the Win-10 message that the app would be closed.
At that point I have changed the anti-virus settings, allowing AVS to be excluded from control.
The few applications I tried so far, gave no moe error message.
So far, so good!
Kind regards.