[mythtv] no more live tv

[Mike Schrag]

I just upgraded to the latest-and-greatest.  When I click on Watch TV, 
the video window never opens and I get the following output on mythbackend:

Changing from None to WatchingLiveTV
Backend stuffed up in RequestRingBufferBlock
IOBOUND - blocking in ThreadedFileWriter::Write()
Backend stuffed up in RequestRingBufferBlock
.
.
.
Backend stuffed up in RequestRingBufferBlock
.
.

Let me know if you want any particular debug info.  This is a PVR250 
system, by the way.

ms