The loop is a command that enables
different loopbacks; local (which it
looks like is what you have configured),
network, payload, and remote (although
the exact options do depend on the HW
being used). Regardless, "no loop"
should remove the command. Make sure that you
have recent code, and ensure that the
network does not have any loops in place.
You might even disconnect the cable,
shut the interface, configure "no
loop", unshut the interface, and see
if the command is still there.
