just wanted to mention that i am having the same problems with the newest firmware.
i taped 5 breakfast shows since the firmware upgrade. the microtrack only worked for 2 shows of the 5 flawlessly. all were 24/44.1 except the 2nd show that came out ok, that was 16/44.1. we were in flagstaff and i taped the opener and both breakfast sets just fine that night.
on 2 nights the microtrack just turned off after about an hour to 70 mins into second set. in san diego the microtrack turned off on its own during both sets and my microdrive turned out to be empty at the end of the night. i was pissed because the other taper lost the first set and a friend of mine sat in with the band for first set.
i also had some problems since the update where it would freeze while writing a file. didnt happen saving a live recording, but it did happen before the flagstaff show while i was setting up. i got scared, so i switched from 24 bit to 16 bit because i wanted to take as few risks as possible that night because there were guest sit ins that also needed to be taped and i was the only taper in the house. plus i was shooting video that night and i wanted a separate audio source for it.
i am not happy with m-audio right now. i had some minor issues with previous firmwares, but nothing like this. the microtrack is not reliable at all. fortunately there were tapers in the house when i had problems, but we lost the 1 set of the tour that i really wanted taped.