Moderator Post (s) for this thread: >No Habla........bydoug seibert on 12/15/2005
Most likely your PTO clutch is bad. I would describe the clutch as an electromagnetic coil that engages when power is applied. When they go bad they act as a direct short when engaged.
Good luck and get your wallet out. Some clutches costs about $275 if you do it yourself (others have replaceable coils).