Popping sounds when playing music

if I am playing music in Banshee, then try and do something else that requires sound, the sound starts popping very loudly and won’t stop unless i reboot my computer. I have tried going from ALSA->ESD->PA->OSS and every combination you can think of (with rebooting after each change). Sometime I don’t get sound at all and the rest of the time it works until I try to use the sound card with more than one app (even with pulse audio!).

The chipset is Intel HDA with Sigmatel, openSUSE 11. Any help is much appreciated. I can supply more info if necessary.