using a venue 8 pro 5830. From time to time, when I start file explorer, it does not find the folders that should show in the right hand part of the screen and when I touch a folder in the left hand part, the screen greys out and the header shows file explorer not responding. the tablet is then locked up and after a few minutes reverts to the start up screen. normal service then ensues. Any ideas on how I can resolve this?