Hi everybody,
I had the same problem, until yesterday!
I bought a brand new SD-Card a few weeks ago and had the same problems (formatting okay, but every access leads to a reboot). Yesterday a friend of mine gave me an old SD-Card and with this SD-Card everything works fine.
Surprisingly it is a SD-Card from the same producer. So the both Cards look identically from the outside.
I think it is a matter of timing problems. Maybe the new cards are too fast.
HTH