Comment 129 for bug 301755

Any version of Pulseaudio after 0.9.15-4ubuntu3 (i.e. 0.9.16 and above) has this problem for me. Regular desktop sounds are about half-half crackly noise, and MPlayer doesn't play proper sound at all. Downgrading back to 0.9.15 solves it.

Karmic's official release is awfully close. You'd better do something about this problem quickly. Pulseaudio is a rather important part of the current desktop.