Comment 7 for bug 326205

@Daniel T Chen :

Do you find this symptom to be constant, or do the glitches resolve gradually during/after the login sound plays?
-> glitches only in gnome login

Also, if you change line 61 in /etc/pulse/default.pa to read:
load-module module-hal-detect tsched=0
do the symptoms disappear when you log out and back into GNOME?
-> yes after modifications+reboot

What versions of pulseaudio and libasound2 are installed?
-> libasound2 1.0.18-1ubuntu4 + pulseaudio 0.9.14-0ubuntu4 and gstreamer0.10-pulseaudio 0.10.13-2