I noticed a strange thing yeasterday: I can't minimize the sceen like i did before, by pressing the button with a windows symbol on my keyboard. Really, I need to exit the game now any time I want to do something else on my PC, so inconvenient. I'm working mostly in CAW now, I haven't installed any CC and software, it just happened for no reason and I don't know how to fix it, any suggestions?

Try alt+enter to toggle between windowed mode and fullscreen.

I've fixed that, thank you. The problem was caused by a sorta toolbar/plugin that I accidentally downloaded at one of the sites, I deleted it and the function is back.