I had to rebuild the slave frontend box by my TV, as it seemed to have been compromised via its wireless connection (which I have eliminated). There have been no signs of compromise on my master backend. I am using Debian Squeeze, but with much of it customized. The kernel is 3.8.3, and the kernel config is a copy from my master backend. I compiled mythtv 0.26 from scratch on both machines. I am able to run "mplayer /dev/video0" so I don't think this is just a permissions issue. I did try an clean install of Wheezy using mythtv 0.26 from the repo, and that was the same. There is no mysql server running on this slave.

Anyway, new installation, slave frontend, it connects to the backend, and I can watch videos just fine. My nfs mounts are OK. Lirc works fine. The "v4l" and "v4l2" commands work. When I try to run "Live TV" from the slave, it will attempt to use the tuner on my master if it's available. But, if I'm already using the master tuner, it says "all tuners are currently busy". I have tried it with both an HDPVR and a PVR150 with the same results. I have also tried deleting all tuners and re-adding them, to no avail. This is on a 64-bit system, as is the master backend.

What other info can I provide? Where can I look for errors? Could there be something in the database? I'm about at the point where I start the tedious process of inserting debug statements in the code to try to figure this out, so any help would really be appreciated.

No-one has any suggestions? Any ideas on whom I could turn to next? I got no response on mythtalk, either.

Added for future reference:

I think it may have been related to a bad logging option for mythbackend in /etc/init.d/mythtv-backend. At least when I fixed that and restarted both backends (master first) the problem went away.