[LAU] Problem with qsynth: noise

Hello, I'm seeing that as soon as I trigger a sound on qsynth (eg. a drum pad on the Axiom 25) the audio gets garbled a lot, becomes very noisy, and I have to terminate qsynth. qsynth version 0.3.6-2, Linux Mint 14 64bits. fluid-soundfont-gm and -gs version 3.1-5. It actually recently started to do that once in a while, and now it is unusable as it immediately outputs growing noise as soon as a note is played. A bit strange because usually software does not get worse like an old car can. I've shut down Ardour, and started qsynth and now it does that by itself, after a few seconds. Like a highly distorted growing larsen effect, becomes bery loud, and then fades away in crackling bits. Then the audio cannot be used. If Ardour was playing, the Ardour sounds becomes fully distorted with crackling asounds. Have to stop qsynth, then the Ardour audio becomes normal again. When qsynth is stopped, there's a click and audio becomes normal. Using qjackctl, I disconnect all audio from system and PulseAudio Jack Sink. All MIDI also disconnected. When I started qsynth, two connections were made from qsynth to playback1 and 2, which is OK. And then after a few seconds noise appeared. W/o any note being played. There does not seem to be an update to the qsynth package (at least in the scope of Linux Mint 14). Hopefully, other people have noticed this problem !