Maybe next time, if there is one, you can just try to
restart ALSA
rather than reboot. If ALSA restart doesn't work, then try some
other things, I wouldn't know what, to see if you can get it going
again. This is just a generic debugging method that I'll use in lieu
of reboots. It sure helps to isolate where the problem might be,
whereas a reboot obscures where the problem might be.
yes I should try that - thanks :) I'm going to try recreating the problem
tonight. I'm not sure if I'll ever see it again or not...