One of the tv cards in my mythtv backend requires the driver to load firmware at boot time. The driver for this card was crashing repeatedly so I have been keeping an eye out for updates. The firmware received an upgrade a few months ago but it was still crashing and it was weeks before I realized that the old firmware was still being loaded. It turns out that you have to actually remove the power from the system before it will reload the firmware. A reboot is not sufficient. This really needs to be in BIG letters somewhere on the linuxtv site.
Anyway I now have a whole month of uptime on the backend. This is only the second time I have had the system so stable in the 3-4 years I have been running mythtv.