hmm ... I still get the impression that it's a playlist issue. I know winamp also uses or can use playlists. Have you tried removing the listing from winamp of the song, then re-adding from the new location?

Also, does the new location have same user permissions to the one you were using on F drive? Check user permissions in both locations.
eg: one location might be set to your user account permissions, and the new location to another user who might be admin account only permissions. This can be changed via the control panels.