I spend most of my time in Linux, inside VMWare, but I do use Windows for a few things like music. (VMWare’s sound drivers are a little unstable.) I use Windows Media Player, since I’m lazy and it comes with Windows.

Recently I had to switch Windows users on my computer. To get back all my stuff, I had to copy all of the files in C:\Documents and Settings\olduser to C:\Documents and Settings\newuser.

This worked surprisingly well, except for my playlists. When I started WMP, and when I tried to play any playlist, it complained:

Windows Media Player encountered an unknown error. This can occur when another program or operating system component encounters a problem but does not communicate the nature of the problem to the Player.

I first realized that a number of playlists (.wpl files) were in C:\Documents and Settings\All Users\Shared Documents\Shared Music\My Playlists, so I copied those into C:\Documents and Settings\newuser\My Documents\My Music\My Playlists.

Second, I looked inside the playlist files themselves. A number of them had olduser’s playlist directory hard-coded. So, I changed every line like this:

<media src="C:\Documents and Settings\olduser\...

to this:

<media src="C:\Documents and Settings\newuser\...

(There were a lot. Thank god for emacs search-and-replace in dired-mode.)

Now, when I ran WMP, it showed multiple copies of each playlist, but it still complained and wouldn’t play them.

After some more head-scratching, I realized that it was caching the playlists in its database. I went into C:\Documents and Settings\newuser\Local Settings\Application Data\Microsoft\Media Player and deleted *.wmdb. When I restarted WMP, it rebuilt the database from scratch and it was happy again.

Moral of the story? Don’t change Windows users if you can possibly help it. It’s really painful.