Well, I'm going to guess that it's an issue with your players.ini file, ie. the logitech kybd config file.
As long as the winamp desktop/start menu shortcut properties leads to:
and .m3u playlists are properly associated with Winamp
Prefs -> File Types: select M3U
Windows Folder Options -> File Types
M3U -> Advanced
Play in Winamp -> Edit
App used command line:
"C:\Program Files\Winamp\winamp.exe" "%1"
and winamp.m3u in the Winamp dir does not have the read-only attribute,
then I honestly can't think of any other reason for this happening.
thread might be useful?