I just installed R5A12. There were no errors, but the install ended by simply dropping me to a root shell promt. When I rebooted I got an error about no operating system (or maybe no bootable disk, I forget).

The problem was easily, but not intuitively, solved. I ran the following commands:

chroot /mnt/hdinstall /bin/bash
lilo

Then I rebooted and it worked. The Myth program has crashed a few times and I haven't figured out how to get any output from my PVR350 yet, but it's at least able to record and playback via video card/VGA monitor.

BTW, this is my first ever successful MythTV install. I've tried a few times in the past and given up. Actually, I think the last time I gave up it was this exact same problem on different hardware. I didn't know how to fix it back then.

My current hardware is:

Dell SC420 small business server (with a free upgrade to a 160GB SATA drive)
Hauppage PVR350