system hangs when using mythfrontend

At NCIX in Canada, there's an option to buy the 120G HDD with linux limpus for $339CDN. I immediately put Kubuntu Hardy on a separate partition using the AspireOne Ubuntu wiki and installed mythfrontend. It drives my 37" LCD TV out the VGA port and works great. (I bought this unit to double as a near silent front end and a portable device when I'm away from home.)

I have one major problem I haven't been able to solve however. While I'm watching recordings in myth, at some point (10s of minutes or up to some hours) the video suddenly scrambles or I get a blank screen and the system hangs.

I've gone through every log in /var/log and my myth frontend logs and I see absolutely no reason for this - no warnings, no errors, no nuttin.

It doesn't seem to be overheating since the case is only barely warm even after hours and hours of use.

So now I have a problem in that I don't know if this is flakey hardware or flakey software. I have all the latest updates installed.

Anyone have any ideas or suggestions on how I can track this one down? I love this little machine and I hope I can solve this since everything I have done with it so far has gone so very smoothly...