Wd tv live streaming can't play any file

Hello. I bought 4 WD TV LIVE STREAMING Players, 2 for my home and 2 for my work and all of them every one or 2 days say that they can’t play any video, music or photo file they played before from 320gb usb hard disk. I reset, upgrade to the latest firmware, but nothing. The only thing that work is to clear media library (does not matter if it’s on or off) and shutdown and remove from power plug. When I restart it’s ok and after 1-3 days the same. How can I fix this? Thank you.

Hi, have you identified if the problem happens randomly or after playing an specific file?