Multiple strange mythtv problems, mythfilldatabase crashed with SIGSEGV in MythContext::ClearSettingsCache()

Binary package hint: mythtv

I've been having a number of problems with mythv, and I'm not sure how they're related. The first problem I noticed was that I couldn't record on two channels (5 and 11). I could watch video on them, but recording wouldn't work. So I tried running mythtv-setup and both of the channels disappeared. On subsequent attempts to run mythtv-setup it would get about 75% through and then crash, dumping a number of these to dmesg:

[ 525.736467] DVB: frontend 0 frequency 861000000 out of range (54000000..858000000)

I also find that I see a lot of messages like this:

[ 326.904764] cx88_wakeup: 6 buffers handled (should be 1)

In addition, the video quality has been, as of late, very poor, and I have a signal/noise ratio near 10-15%. I've tried adjusting my connections but nothing seems to help. I use a DVICO HDTV5 Fusion with Time Warner cable in NYC. I started experiencing this problem about a month ago, soon after upgrading to Intrepid, and I've experienced it on kernel versions 2.6.24 and 2.6.27. I'd be happy to add any additional information that may be helpful. Thanks for your time!

ProblemType: Crash
Architecture: amd64
DistroRelease: Ubuntu 8.10
ExecutablePath: /usr/bin/mythfilldatabase
NonfreeKernelModules: ath_hal nvidia
Package: mythtv-backend 0.21.0+fixes18379-0ubuntu1
ProcAttrCurrent: unconfined
ProcCmdline: mythfilldatabase
ProcEnviron:
 SHELL=/bin/bash
 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/X11R6/bin/:/opt/local/bin:/usr/local/bin/:/usr/X11R6/bin/:/opt/local/bin:/usr/local/bin/
 LANG=en_US.UTF-8
Signal: 11
SourcePackage: mythtv
StacktraceTop:
 ?? ()
 MythContext::ClearSettingsCache ()
 MythContext::readyRead ()
 readyReadThread_iffound ()
 MythSocket::readyReadThread ()
Title: mythfilldatabase crashed with SIGSEGV in MythContext::ClearSettingsCache()
Uname: Linux 2.6.24-18-generic x86_64
UserGroups: adm admin audio avahi cdrom dialout dip disk floppy fuse gdm lpadmin mythtv plugdev pulse pulse-access pulse-rt root video