I am at the same situation. Same exact behavior.
While email support was helpful, calling Sandisk resulted
in an offer to warranty it from Sandisk (which I will be doing
this week once I can get to the UPS store on thur/fri.) They even
supply a 3-dayish prepaid UPS mailing label.
I mentioned this forum several times talking to the phone support
tech 
They could just be a few bad parts. One location in memory stuck
at 0 or 1, which agrees with one firmware, but is the wrong value for
the next could do it.
-r
