USB Mouse/Keyboard loose power often, works fine when replugged

I have a weird problem, My Mouse looses suddenly power when I am working and this happens frequently. It starts working if I replug the USB. Same goes with the Keyboard on a different USB port but fortunately not that frequently. But these two ports works absolutely fine if any other USB product is connected (I have tested with a Hard Drive, a Pendrive and a Phone connected via USB). Now, I have only two USB ports on my macbook pro.

Another test, I have a LCD screen which comes with two USB ports (Which takes power from macbook pro), the above same problem applies here. The Mouse stops working frequently in both of the ports frequently.

Must be the mouse and keyboard.
I know it is so obvious, but I've never heard of this.
If it is really giving you a lot of trouble, get a new keyboard + mouse?