Hey,

I just run into the same/similar problem and unfortunately it is not solved yet.
Out of the blue I do get those error message (together with not enough power fromUSB to charge device, but afterwards it charges). And I cannot get a mass storage connection to the PC (2 types, different cables). I checked lsof, but nothing from MyDocs after reboot.
The MyDocs gets unmounted, but keeps unmounted even after unplugging USB.
Furthermore on the PC the number of drives enumerates up to 6 drives, but all are empty.
After unpluging MyDocs keeps unmounted.

I also played around withmodules g_nokia, g_ether, g_file_storage (resp. th different connection modes) in various orders.
All to no avail.

I really would appreciate any help.

P.S.: I thought it was ubiboot (latest version just upgraded), but I went back to an older version where I definitely did nothave this behaviour. Still the same.

Only difference I can now imagine/remember is that I have once/twice booted to FirefoxOS, but hey: Nothing to do with, or?