Have the same problem. Sandisk 8 Gig micro.
My 810 will not start up as long as this is inserted. However it will mount to my Mac desktop when removed and mounted on its own.
Tried another 2 Gig micro and it starts up fine. Hard to believe the 8 Gig would get corrupted so easily.
How can I get the 8 Gig to be useful again?