When I tag mp3 files, Windows Media Player stops working

I have downloaded some mp3 files from youtube. I can play them with Windows Media Player. These files don't have a Title or Artist. I cannot add those in File Explorer, those fields are not editable. I can tag them with MP3TAG. However, when I do that I can not play them with windows media player, I get an error message "Windows Media Player encountered a problem while playing the file." When I look in File Explorer, the title and artist file are still empty. If I remove the tagged fields in MP3TAG, Windows Media Player works again.

Any suggestions?

a) use the suggested tools to check your files for integrity.
b) see here:

There is no download option from YouTube. I believe you have likely used a 3rd party online converter tool. This is the source of the problem for this and several other recently reported issues. See the link posted above for more info.

Removed several posts that linked to outdated YouTube converters. If you're looking for something like that, please use the search engine of your choice.