[CentOS] Skype and problem with ALSA mixer driver?

Having used skype successfully in the past with previous CentOS
versions, I haven't yet been able to get it working fully with CentOS
5.3 - the playback sound works OK but I can't get the mic working. I
previously used the skype version installed with yum from the skype repo
but thought maybe this was faulty, so have just installed the static
version (cd skype_static-2.1.0.81). However, the mic still doesn't work
and I've notice the following (repeated) error messages on the command
line (currently this version has to be executed from the command line):

snd_pcm_avail_update() returned a value that is exceptionally large:
203032 bytes (1057 ms).
Most likely this is a bug in the ALSA driver. Please report this issue
to the ALSA developers.
snd_pcm_avail_update() returned a value that is exceptionally large:
201176 bytes (1047 ms).
Most likely this is a bug in the ALSA driver. Please report this issue
to the ALSA developers.
snd_pcm_avail_update() returned a value that is exceptionally large:
199280 bytes (1037 ms).
Most likely this is a bug in the ALSA driver. Please report this issue
to the ALSA developers.

..........etc

Does anybody have any information about this issue/bug and any idea how
to solve the problem?
Thanks,
Andy