I have seen this happening a number of times:
the M128 runs fine for a long time and then one day when you switch the circuit on, it is dead or it is just funny. If you re-download the firmware, everything is cool again. This happens with both the bootloader and application firmware. If I enable the on-chip BOD, the problem is much better, but it still happens now and then, so this shows me that the problem has something to do with brown-outs, and also that the on-chip BOD is not that great.
anyone with experience on this matter?