[mythtv-users] Weird tuning failure

[freedenizen]

So I have an intermittent recording failure on one of my HD-PVRs.  The
issue seems to be tied to tuning in some way although I'm not quite
sure how.  I use firewire to change the channel on the cable boxes.
When I have a failure I see the following in the logs:
2010-11-03 18:30:02.188 TVRec(4): Changing from None to RecordingOnly
2010-11-03 18:30:02.190 TVRec(4): HW Tuner: 4->4
2010-11-03 18:30:02.274 Launching: @L2
2010-11-03 18:30:02.276 PID 27646: launched
2010-11-03 18:30:02.278 AutoExpire: CalcParams(): Max required Free
Space: 23.0 GB w/freq: 15 min
2010-11-03 18:30:02.279 Started recording: Futurama:"War Is the
H-Word": channel 6745 on cardid 4, sourceid 6
sh: @L2: command not found
2010-11-03 18:30:02.281 scheduler: Started recording: Futurama:"War Is
the H-Word": channel 6745 on cardid 4, sourceid 6
2010-11-03 18:30:02.355 PID 27646: exited: status=32512, result=127
2010-11-03 18:30:02.372 SignalMonitor: channel change failed
...

notice the "Launching: @L2"  each time there is a failure it is
different, for example "Launching: `=2" or "Launching: Â<80>^Y2"
my channel change script for that device points to
/usr/local/bin/channel_rng it looks fine in the DB, on times it
records fine I just see " Launching: " in the logs.
Any thoughts as to what the issue is?  I'm currently running trunk, rev 27073