Line In Line Out Monitor Problem

[Connecticut]

I have a Mbox mini and ever since upgrading to Snow Leopard have had continuous problems with the mbox. For example if I empty my trash can the sound of the crumpling paper will just loop and play over and over. But my main problem is this, I was going to turn off my monitors and accidentally knocked out the left speaker output. Now when connected to the mbox I just get hiss and no sound. If I unplug all the wires to the monitor it makes no noise, but when I connect the wires back you hear the hiss. Everything is fine through the headphones and pro tools runs fine. My monitors just don't work. Is it possible the mbox line in/out is fried? Thanks for the help in advance.