I have a fairly new installation of Mythbuntu. I have noticed several times that my machine has locked up hard with the sound card playing a sample repeatedly ... cannot do anything but power off --- could not ssh into the box.

The last time it happened playing a DVD.

I have also had X restarting on this box for no apparent reason as well.

Anyone have any suggestions?

I have run mythtv on a normal Ubuntu system, and it never had these problems.