we are using several PicoMOD 7A, which are suddenly freezing after minutes, hours or days.
Freezing means that the device is not pingable anymore. There is no reaction of the device in any way.
The last line of the logfile is: NI2C: Failed to wait for 'not busy'(iicstat=b1)
After this thera are only a lot of dots ".".
As attachment you can find the logfile we recorded on the serial interface with putty.
Due to upload restrictions (1MB max) I removed a large numer of dots "." at the end of the file.