Stoping Other Games

So What Happened I just got minecraft for my PC , It was a-little laggy but I could live with it so I contuned playing but the frame rate was slowly droping , It had taken A long time for me to notice it But I keep on playing , but by then I wanted to play a nother game with the bad frame rate and all, so I went to play Assassins creed ( for PC ) and it didn't work very well , so I changed it to spore , It was the same , So I shut it down For the night , the next day nothing was working , not even minecraft .

And I think minecraft triggered it