Apparently Windows Server 2003 sets the frequency for either mc or pi
voice to zero, which in turn triggers a call to audio_bug from this
chain:

open_voice -> AUD_open_in -> audio_bug (audio_validate_settings):

A bug was just triggered in AUD_open_in
...
Context:
audio: frequency=0 nchannels=2 fmt=S16 endianness=little

But since no attempt by the said OS is made to actually use the voice
with zero frequency this can be considered normal behavior.

Hence if zero freqency situation is encountered - close current voice,
and make noises if the guest tries to use it.

Reported by simon@...ve


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4694 c046a42c-6fe2-441c-8c8c-71466251a162