[mythtv-users] RingBuf error -- how to troubleshoot?

[Christopher Couples]

All,

I've been chasing my tail round and round all day. When I invoke 
mythfrontend
(latest svn build), this is what I see:

2006-05-13 19:21:23.651 TV: Attempting to change from None to WatchingLiveTV
2006-05-13 19:21:23.659 Using protocol version 29
2006-05-13 19:21:32.251 RingBuf(/mnt/MythVIDEO/tv/1003_20060513192125.mpg):
Invalid file (fd -1) when opening 
'/mnt/MythVIDEO/tv/1003_20060513192125.mpg'.
2006-05-13 19:21:32.320 NVP::OpenFile(): Error, file not found:
/mnt/MythVIDEO/tv/1003_20060513192125.mpg
2006-05-13 19:21:32.323 TV Error: StartPlayer(): NVP is not playing 
after 20000
msec
2006-05-13 19:21:32.481 TV Error: LiveTV not successfully started

This indicates some sort of RingBuf issue, right? Trouble is, the file 
that's
referenced _is_ where it's supposed to be, with permissions which should 
allow
mythtv to write to it.

Hardware is Comcast/Moto DCS-3412 via firewire. Plugreport gives:

[mythtv at couples-devel ~]$ plugreport
Host Adapter 0
==============

Node 0 GUID 0x00309500a0030fd9
------------------------------
libiec61883 error: error reading oMPR
libiec61883 error: error reading iMPR

Node 1 GUID 0x00152ffffed0294b
------------------------------
oMPR n_plugs=1, data_rate=2, bcast_channel=63
oPCR[0] online=1, bcast_connection=0, n_p2p_connections=0
        channel=0, data_rate=2, overhead_id=0, payload=376
iMPR n_plugs=0, data_rate=2

So I want to diagnose this, but I'm not sure which of the -v options to 
use to
start to try and chase this down.

Can anyone help me, either with the switches, or the problem itself ;-)?

Thanks,

Chris Couples