HELP PLS: D

so my computer has been getting really slow lately due to all the shits thats on it so i DL CCleaner ran it etc and my screen turned a light shade of blue, its doing my head in and wont go away! ( I DONT KNOW IF IT WAS JUST WIERD TIMING)

so i googled it and from what i read, the cable was simply loose... so i fiddled with it.. not fixed.

Just wonderd if there would be any other reason why this would be happening ?

Thanks xoxoxo