I just ran into a very strange problem that almost caused me to reinstall my OS:
I installed QtCreator with a MinGW toolset fresh from the Qt-Homepage. Everything worked as expected and I created an empty Hello World project to test things out. From then on it got ugly: When starting the project QtCreator froze and I wasn’t able to delete the generated .exe file.
I did some research and found nothing of help. There were some issues with early Windows 10 builds or some users having incorrect runtime environments. In the end it turned out that the issue was caused by Avast 2015 – It blocked all Qt-based executables, whether they’re started by QtCreator or directly.
I turned off active filesystem search and was able to use my executable. Hope this helps someone out there experiencing the same issue.