Alt tabbing and closing progams cause huge problems

So I alt tabbed to close down my music playlist and then i go back into league and my camera will not lock, then i try ctrl alt delete to open task manager and then my game wont allow me to input any commands and goes into full screen windowed mode. Why does this happen?!?!?!?!?!?!?!?!??!?!?!? Super annoying and it made me die to gromp level 1 cause I couldn't even control my fucking character. I had to log out of my computer and log back into gain control of anything because when all that shit happened it wouldn't let me ctrl alt delete anymore. This isn't the first time this has happened either, I don't know what causes this shit, but it needs to get fixed.