Corrupted video files

I just bought a WD MyBook 4 TB external HD to help store additional TV shows and movies.  However, when I transfer the files from my internal hard drive to the external, they become corrupted and unplayable.  I’ve searched for a solution and can’t seem to figure it out.  Any advice would be appreciated.  I’ve already exchanged the drive a couple times thinking the drive itself had failed, but no difference.  I can copy to my other external hard drives without issues.  

Hello,

Try formatting the external drive. Also run a diagnostic using WD DLG.

Thanks for the recommendations.  Did both things, no errors.  Still having problems playing the video files off the external HD.

Hi.

I have nearly the same problems - i copy photos and short films. But strange - one OK, other NOT, no matter of their KB!

Then i tried like you few movies - and, for ALL was problem found.

OK, I said to myself → don’t copy illegal movies … but I do like have MY films and memories… 

maybe if we change from .avi → .mov ? 

THANKS