Fixing the sound in Ubuntu 9.10 Karmic Koala after replacing the motherboard or sound card and the computer freezes

Just run this command:

sudo aptitude --purge reinstall linux-sound-base alsa-base alsa-utils linux-image-`uname -r` linux-ubuntu-modules-`uname -r` libasound2

It worked for me (although it did freeze one more time after doing this, but after I restarted again it worked after that). and it's documented in this link here if you don't believe me: