SPD One Wav is too sensitive and triggers itself

[leandermusic]

Hi all. I need some help with the SPD One Wav. I've easily uploaded my wavs to the slots and the playback just fine. But any vibration around the unit causes the playback to start again. Even a heavy foot step will cause it to skip back to the beginning or when not in use, start playing out of nowhere. I've tried messing with the threshold and sensitivity knobs, to no avail.
I uploaded my pieces with the _m suffix, does this have any bearing..?
At the moment the unit is rendered useless by this problem.
Can anybody explain to me what I'm doing wrong
Thanks in advance
Clive