you can still turn the unit off while the hold switch is engaged.
Not on mine you can't. Everyone should check theirs rather than trusting Simpy. He may have a bad unit/hold switch for all we know.
Can't get mine to turn off either.
just tested mine, if the hold switch is on, pressing the power button gives the message "HOLD switch is on"
however, if I hold down the power switch for about 10 seconds, the unit will shut off (this is the same amount of time needed to shut off the unit after it has frozen).
and if the hold switch is on, when I try to power up, it gives me this message:
"M-AUDIO (next line) Hold key is active" and then the unit doesn't power up.
based on this, I'd say that if you're power button got stuck or something was constantly pushing against it, the unit would turn off. but it seems to me that that would be difficult. my power button doesn't feel like it'd get sutck in the pushed position very easily.