Is Mandriva better or worse? and Why? or what Linux Distro is the most stable? Is it worth the change if so?
Not worth the change as you have shown you are not yet prepared. Talking about "stable" all versions are stable when they are submitted by the team as such. GNU/Linux is stable talking about the basics; what mostly isn't stable are the "newbies" like us who need more time "learning" in order to arrive into solutions over simple configuration like "sound".
I have one extremely stable: GNU/Linux-Slackware 12.2; it is rock-solid. But this is not for those who cannot even configure an Ubuntu to play sound.
My suggestion is for you to interact with Ubuntu community forum where sound problem is abundantly given answers. Ubuntu is debian based, there are debian documentations and how-tos, click this link
Hope this helps.