Problems playing video files

I transferred a couple of TV shows to my Seagate external drive to watch via my WD Media player. The first 9 episodes of the first series played OK, but when I came to play the 10th it wouldn’t play due to an invalid format. All the files were in mp4 format. I then tried other shows. Ones I had watched previously were OK but any new ones would not play whether they were mp4, avi or mkv. These files play fine on my PC. I tried resets etc with no luck. I even tried swapping the USB sockets to which the two hard drives are connected on the WD but it made no difference.

I then tried copying the original files that i ad a problem with to another (Iomega) external drive. They now played fine via the WD media player!. I’ve tried connecting the Seagate drive to my PC and playing the files directly from it and they play fine.

So do I have a problem with my WD media player or with my external drive? I’ve had the WD player for a number of years and apart from needing to do a few resets I’ve never had any problems with it. I’m prepared to purchase a new one - or a new external drive but I need to know which one is at fault. It seems to be the external drive, but then why do the files play OK via the PC?

Any ideras / help would be appreciated.

There’s  a known bug that one invalid file will stop any good files from playing until the device is power cycled. Maybe it’s happening here too?

Forgive my ignorance, but what exactly do you mean by a power cycle. I’ve switched off the media player, and after a while powered back up with no luck.

If a dodgy file can cause others not too work why do some work and others not. How do I identify what is the dodgy file?

Powercycle means disconnecting it from power and plugging it in again rather than just turning it off with the remote. You identify dodgy files by playing them. If the file plays, it’s fine. Alternatively you could use Mediainfo to compare specs on each file but even then a file with proper specs might be encoded badly and cause the WDTV to hang.