Files being emptied/locked

I have a new 4TB My Book that i use to store all my media and I’m seeing files changed to a folder with a lock and they are empty, the error say’s- H:Big Screen\Defiance\season 1\Defiance.S01E09.HDTV.x264-EVOLE.mp4 is not accessible. The directory name is invalid.

 I’m now seeing other stored files turning the same way, what am I doing wrong?

Hello, are you conecting the My Book to a WDTV? If you are, see if the following link helps.

All my firmware was up to date.