I had been facing the same problem of memory card eject some days back.
I simply took the back up of data and formatted the memory card once, Since then no problem found. Hope it works for others also.it has been 15 days
since then.try it and After updated to 6.0 camera is automatically capturing image and closing it automatically. And some apps also opening and closing automatically. Please any one give solution to fix it. I restore the phone also but I facing the same problem.