I have no problem in opening the files.
jmarkt
I hope you forgive me being, just a little, pleased with your post. I was waiting for such a post today because ...
today is the day after Microsoft Tuesday and the problem you are reporting is precisely the same one I have reported as being associated with the period, every month, that Microsoft makes available its critical updates and, all too frequently, has to control access to servers to prevent overloading them. Unfortunately, the way they delay users from accessing their servers at system startup does, I believe, also interfere - for some users of avast - with avast's ability to perform its VPS updates at startup.
This explains why it is spasmodic, once you have downloaded the Microsoft updates for this month then the problem will go away.
Ah, it is a sign! I just got the popup from Microsoft to say my monthly updates are ready to be installed. Honestly .. just this second ... it hung around for ages earlier today because they are limiting access.
The avast folks have made changes in the new release (currently in beta - see the top of the forum) that modifies the way avast works at startup and to the way the VPS update works. It will most interesting to see if you continue to experience this problem on future Microsoft Tuesday's or if the avast folks have managed to overcome this issue.