Unfortunately I have to report a very similar issue like dieterstoll. I bought the unit one year ago. After one year of normal operation, I suddenly experienced the screen freezes a few times. Sometimes I also get the "Error: App Returned With Status 1xx" message at boot (don't remember the number any more). Once I also observed that the unit suddenly rebooted itself while having a gig. Fortunately all the channels stayed open.
To be honest, I don't trust the device any more. In case I have a marriage ceremony, I fear that it migth suddenly crash. That would be horrible!!!
Additional I would like to mention that when I bought the unit, first it turned out that channel 6 sometimes suddenly became active, even when nothing was connected. I immediately returned it to the dealer and got a new one after 4 weeks :-( !!! Not to talk about the issue that I can operate the WIFI stick only on channel 1 (no other channel works). Event though it is the Samsung stick that is recommended by Line 6. The support was unfortunately not able to solve this issue.
I'm really disappointed, even though I like the the possibilities that the M20d offers very much. But always having some kind of trouble with a device for which I payed about 1800 EUR is not fun at all. :-(
Could somebody from the Line 6 team at least tell me what I can do to speed up sending/returning the unit and not having to wait 4 weeks again. I have a gig nearly every weekend! This hurts very much at the moment! Apart from that I read that dieterstoll got the unit back with just a SW update. Great!! How can I avoid to get it back with the statement "everything works fine"? Unfortunately there is no way to reproduce the issue. Sometimes it happens at boot, sometimes after a few hours and sometimes not at all.
Regards,
Bernd