Why on earth is WMP allowed to go through your music library without consent and start changing tags to conform to its own database of tags? I reinstalled Windows 7 recently and forgot about this stupid "feature" and didn't uninstall WMP in time. When I got home, I noticed many of my music folders were listed as modified that day, which was odd as I hadn't been home. Then I remembered what WMP likes to do in its spare time - ruin hours of tedious tagging. Literally thousands of my mp3s had been retagged, with a bunch of worthless album art in the folders. A few characters in a bat file removed all the album art, but it's going to take a long time to retag the mp3s (which is necessary if I want my proper media player's library to function). Thankfully WMP can't handle FLAC, so the majority of my music is safe.
Obviously it's my fault for forgetting about this, but come on Microsoft. This is ridiculously intrusive, and also extremely sneaky, though to what end, I don't know. There is no mention of this when adding folders to the Music library. I know there's an option in WMP itself, but it will start retagging even if you never load the damn thing.
Just a rant I guess, as well as a warning: cripple WMP before it gets to your tags.