After a clean boot login I need to logoff and login again to start working. Otherwise I cannot move icons (just to name something simple!). UAC is set to the lowest setting and I am logging in as administrator, using Windows 8.1 Pro. Once I'm logged in properly (the 2nd time), everything works perfectly!

I checked almost all software, latest updates, malware, virus, new drivers, etc. but I'm running around in circles. Where should I start looking for the cause of this weird behavior?

Regards, Gerrit