No media will play, show 00:00 duration

[Dual]

I play almost exclusively MP4 files. In recent months fewer and fewer files successfully opened on a double-click. I had to double click on the playlist item or select play in the playlist. Now nothing plays. Every item shows a 00:00 duration in the playlist. I tried resetting and it hasn't helped.

I have tried searching for this problem, but I really don't know how to phrase/parse the request; and thus this post.

Hoping someone can help. Thank you very much.

[fkuehne]

Did you move or rename your files in the meantime and the playlist was not updated?