Marcus,
this is a problem with the
gnuradio/gr-audio-alsa/src/audio_alsa_source.cc. I ran into a few
weeks ago and i managed to find a quick and dirty fix for.
I'm assuming that you're stopping the flow graph and restarting it
again. if you look into the "check_topology" method. There's a FIXME
there, what I beleieve is happening, is that when you try to restart
the flowgraph after stopping it GNU Radio is trying to reset your
sound card and it thinks that it's in a corrupt state.
My fix was to add a "static bool" variable that skips the
"snd_pcm_hw_params(d_pcm_handle, d_hw_params);" function call. the
flag is "static" just so you can detect your first entry. After that
run make and make install and things should work fine.
al