Game freeze up on Startup

I have a bit of problem when I start my game. Upon starting the game , the game freezes but when I press Alt + Tab , and check the background , it seems to work fine but when I enter the game . It again freezes but the screen changes from what it was before. I didn't had this issue 4 hours ago but now it started to occur frequently. Also , i can move around on pressing keys but it doesnt show up on my screen. Please help!
Specs :-
Processor - Intel(R) Core(TM) i5-5200U CPU @ 2.20GHz 2.20 GHz
Ram - 8.00 GB

Edit :-
It has been fixed but I don't understand how the problem occurred , I had to take out my wireless port for my mouse (it was out of battery and not working) and after that it worked properly , I don't know what kind of error it brought to Core game but it might happen again.

If you're using Core Games in full screen or borderless window it may happen. Try to use windowed.