During playing some folders give fault "Folder Empty"

I've got 2 CDJ-850 with the latest firmware and uses 2 identical USB sticks of 128Gb with about 80Gb used space. I only use de Folder search option.
The problem is that during my set suddenly a folder is being showed as "Empty" but a few mintues ago this one was accesable. Sometimes all my folders are Empty, to solve this i must eject the USB and place it back. Than I can use the USB again, but while ejecting the USB my Taglist is being wiped! :-(
Also sometimes if i'm in a folder and i scroll to fast than the list wil stop, example: tracks A thru Z, scroll scroll scroll, than the list stops at M, but i know that are songs on it from M to Z.
Also afer ejecting USB this problem is gone.
But during the set of 5 hours ejecting about minimal 10 times its very frustrating.

I know this problem was mentionted somewhere on the forum but couldnt find it or a solution.