Have you tried the sd reader on the 2.2"?
It sounds to me more like a hardware issue than software. If you have issues with the sd reader as well, I would suspect it's an issue with the power supply filtering on the board.
Looking at the info in the link above, there is a picture of the bottom of the board with a three pin surface mount component and a couple of discrete components around it, right next to the power pins on the connector. Without a good pic to go by, I suspect this is a voltage regulator and some filter capacitors. There could be an issue there. A problem with one of the capacitors could allow noise to cause random events.
It might be nothing to do with this, but it's a possibility that kinda fits the symptoms.