[Bug 38621] Re: After shutting down Rhythmbox, previous Gaim sounds are played

[Richard Laager]

Odds are that your sound card does not support several simultaneous audio streams, even on Windows. Windows is mixing the streams for you.

I'd first try running this:
gstreamer-properties

Then, see what your sound is set to. Try setting Gaim to use the same thing.

Alternatively, you might want to look at this HOWTO: http://www.ubuntuforums.org/showthread.php?t=32063

I'm not sure how relevant that is in newer versions of Ubuntu.
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After shutting down Rhythmbox, previous Gaim sounds are played
https://launchpad.net/malone/bugs/38621