I just subscribe to eMusic.com (awesome, assuming you don't have mainstream music needs), downloaded a bunch of stuff (140 tracks -- I got a bit overexcited!), and then fired up WMP to add them to the library. In a moent of confusion I told it to look in M:\ (which is mapped to \\Server-02\MP3s\) rather than providing it with the UNC path as I normally do.

My schoolboy error resulted in every one of the ~4,000 tracks showing up in the library twice. After a moment's swearing I sorted everything in the library by path, selected all the files on M:\ and removed them from the library. All well and good, except I now had 12 "Unknown" folders in the Album Artist tree, none of them with any tracks in, and for the life of me I couldn't get rid of them -- right-click/Delete... brought up an "Unknown error", and that was about it.

Not to be perturbed I removed EVERYTHING from the library, and even then the "Unknown" folders remined. The MS KB was unhelpful and Googling hasn't turned up anything, so does anyone know where WMP keeps the library database so I can destroy it and start from scratch, or is there anything else I can do?

(To save you the effort, "use WinAmp" or similar is a valid but unhelpful suggestion -- for the most part I like WMP's interface, and this is the first time it's fucked me about.)

I've done similar things using Musicmatch (and I use eMusic too) so its not just WMP that buggers around.

Found the library. It lives, unsurprisingly, in "Documents and Settings\[Username]\Application Data\Microsoft\Media Player". I killed it and started again, and I shall make a safe copy of it for next time I try something stupid. :)

Also I just found a handy registry key. I have a few OggVorbis files and MP4 videos and was irritated that they showed up under "Other media", but the following key:

HKLM\Software\Microsoft\MediaPlayer\MLS\Extensions

allows you to add new file types and put them in the correct category. Every cloud has a silver lining, I guess...

And it's broken again. Fucking thing. (Perhaps I've pushed the database over some sort of size limit?)

Quote from a page...

"If you get a double library listing (which is just a visual defect), just switch away and then switch back to the Library pane."

http://www.nwlink.com/~zachd/pss/pss.html

Tried that. Even closing WMP 10 and reopening it doesn't help...

Now it seems to have become a recurring problem I'd be inclined to ditch WMP10 and try something else, but it appears Media Center uses the same library database and is also fucked up so even if I abandon WMP I'm still in a spot of bother.

Grrrr!