Playlists locked up

[Moxey]

I'm trying to add a song to one of my playlists, but it fails, giving me an "Error saving playlist" message: "Cannot save playlist: Error writing to file or file is read-only."

I've had no previous problems adding songs to my playlists in the 3 months I've been using Winamp. Why now? I have not changed any playlists to read-only, so I doubt that could actually be what's happening here.

Any suggestions? Thanks!