Computer keyboard and mouse help?

So my computer keyboard as well as my mouse have been acting strange lately. on my keyboard everytime I try to play a flash game on my internet browser when I try to move my character with the arrow keys and I take my finger off of the key my character continues moving and the only way to stop it is to hit the same arrow key again. For my mouse it seems to double click when I single click. I have changed out both my keyboard and mouse and attempted to see if it was the hardware that was damaged, yet the smae things happened with the new keyboard and mouse. How would I fix this problem?