Hi, I got this very weird problem. It took a lot of time and nerves to figure out (Centrafuse was acting all weird).
After the CarPC is powered off for a while (probably after the M2-ATX cuts all power), at the first boot the onboard sound is disabled. Rebooting or shutting down and then turning on the CarPC after a little while reenables it.
You can imagine how this is very unsettling. The BIOS has only "Disabled" and "Auto" options for the on-board audio. Mainboard is Commell LV670M with a 2Ghz Pentium 4 M processor.
Any ideas? For now the only solution I see is getting another motherboard, or get a USB audio card and disable on-board audio altogether.