While resolving an audio input problem within Ekiga, here is a message which occured in /var/log/syslog on a Ubuntu Lucid (10.04.1 LTS) :
alsa-util.c: Could not recover from POLLERR|POLLNVAL|POLLHUP with snd_pcm_prepare()
I have not found yet where the problem comes from. After searching through ubuntu fora, here is the solution :
sudo apt-get install linux-backports-modules-alsa-lucid-generic linux-backports-modules-alsa-2.6.32-24-generic
In order to make my webcam audio input work, I decided to reboot my computer. The changes I made just before were taken into account.
I hope this help !