Oh I see
Well my mp3 is this one
http://www.mympxplayer.org/album_showpage.php?pic_id=58
I short circuited the player with a pince and upgraded it to 3.5.37v2.51b.fw with 3.5.37 dump file from the download section
Indeed it must be some residues from previous versions causing my volume up down <> problem
Thanks tadad1