I too have received the 'failed to unmask IDE' error just once with my backup Mk2a never w/my Mk2 & they're setup exactly the same. This happened just yesterday hence the search for error coming to here. I didn't get the low power icon when this happened but it was booting up at the time never getting to the play the music stage after awhile of not hearing anything I looked down to see the error on the screen. No buttons would respond except for pushing in the knob until Hijack options appeared whereby I used reboot machine option & all was well again. On the flip side my Mk2 has never had the IDE error appear but has had the batt icon appear quite frequently, until I can find a higher output alternator that has so far been elusive to find. I know my HO amp is the culprit & having the Empeg vol pumped, blower fan on high, lights on and/or wipers and sitting at idle in various combinations & is the reason the voltage drops triggering the batt icon to appear.