Hi, Travis
You Should Not have 5 volts on the Outer Shell, It's a Gnd/Shield, Pin's 18 through 25 are also Gnd/Returns pin's.
On the Printer Port connector on your Computer the outer shell and pin's 18 through 25 all come together as Ground's.
That's why your BOB board is Shorting Out Everything.
Pin's 1 through 9, 14, 16, 17, are output's used by Mach to send 0 volts or 5 volts to your BOB/motors/turn on and off things.
Pin's 10 through 13 & 15, are input's used by Mach to see, 0 volts or 5 volts from your BOB/system/limits, E-stop switches, speed pulses and such.
Thanks, Chip