Powerbook G4 and sound

Hello,

I've got problem with sound on my Powerbook G4 Titanium
(PowerBook3,5). Sound always cranks and skips when I moving my
touchpad, regardless of the source of sound. It happens in all my
programs, including vlc, mplayer, e-uae and ioquake3 - they show in
the log messeges like "underrun occured" and "broken pipe".
If I remember correctly, this bug appears on kernel 2.6.32-5 (from
Debian Sqeeze) and later. On kernel 2.6.38 from Ubuntu sound works
_almost_ normally (cranks occur rarely).

I used also mpd server, but it breaks after sound cranks (ncmpc shows
"Timeout") and I can only restart mpd server (/etc/init.d/mpd restart)
to get mpd working (for some time).

Log from alsa-test.sh in attachement.

Sorry for my English :)

Best regards,
Петр метель