I am not sure what do you mean with: "Windows 8.1 is at least not the latest version and i would assume that people might have experienced also those problem if it is a general problem.". Not latest version of OS? Not latest version of Qt? System is up to date, and latest Qt installer was downloaded 15 minutes before I posted original version.
No idea if other people have stumbled upon same problem, I hoped someone did and had solution, that is why I posted here. Seems like I have to create yet another account to gain access to bug tracker, so I'll pass for today.