Comment 38 for bug 746023

After debugging this issue with Oliver we got to the following solution:
 * Fix /lib/udev/rules.d/90-alsa-ucm.rule to include the whole alsaucm path;
 * Create a postinst hack that will erase the old alsa state file, call alsaucm and store the new file (the alsa state is restored after the udev rule is called, so it should be removed to avoid the wrong sound card setup);

It's safe to remove the old alsa state file because it's broken with Natty anyway. We should still keep the udev rule in case the user erases the alsa state file by accident, so he can still have a working sound at next reboot.