Heated bed problems

So whenever I plug in my printer, before I even enable the heated bed, a red light pops up under the heated bed MOSFET. Then, when I turn on the heated bed, the whole system seems to malfunction and the USB cable connecting to my computer gets really hot. My printer works fine when the heated bed is not connected, but when it is there are always problems.
Is there something I need to put in the firmware to fix this?

Any help is appreciated


UPDATE: There was a short between the two heater connections. It works now.

Edited 1 time(s). Last edit at 03/25/2015 09:01PM by nickrivera.