Audio Problems when editing videos

Hi to all.

I'm in serious troubles with KDEnlive. It crashes as soon as I load a .wmv video or at least the audio spikes when editing other format. The screen shot (please, see attachment) shows the notification (up on the right) I get just before crashing and (down in the left) the Bug Tracer window that comes out just after crashing. I've been trying to change

Settings -> Configure KDEnlive -> Playback

from OSS to Automatic to Alsa to Pulseaudio but the problem witn .wmv persists. By the way, running 'melt videofile.wmv' seems to work perfectly.

On the other hand, when loading a xvid or avi file KDEnlive does not crash but I still get such a notification. Trying to play the video through KDEnlive player it makes the audio spike or scratch (don't know what's the correct term in my case). I suppose this happens regardless the audio driver chosen in the Playback section (at the moment, i've been trying with PulseAudio and Automatic).

My problem till now has also been difficult to solve because of the long times required to get an answer from this forum or by Mantis. Actually I've been posting similar questions somewhere else in those forums and also received some replies, but after few interactions everyone disappear leaving me still into troubles. For example:
http://www.kdenlive.org/mantis/view.php?id=1299

Remark: this is not a reproach to anyone, but it's just a true part of the story :) Thanks to all of you reading my previous, present and future posts in order to help me and all of those in my same troubles.

Turning to the point: any suggestion, please?
Thanks.

System Infos
Ubuntu 9.10
Kernel 2.6.31-15-generic
Acer Aspire 5730z

lspci | grep Audio
00:1b.0 Audio device: Intel Corporation 82801I (ICH9 Family) HD Audio Controller (rev 03)

kdenlive, kdenlive-data, kdenlive-dbg : 0.7.6-0ubuntu0~karmic4

libmlt1, libmlt++2, libmlt-data : 0.4.6-0ubuntu0~karmic2

mltpython 0.4.7e-0ubuntu4~ppa1k