I've heard via side channels (IRC mostly) about some users experiencing system bus crashes and have been spending a bit of time trying to figure out what it is. Here's an interesting looking crash gathered in Launchpad: https://bugs.launchpad.net/ubuntu/+source/dbus/+bug/164349
According to launchpad bugzilla, it's duplicated with https://bugs.launchpad.net/ubuntu/+source/dbus/+bug/128624, and its upstream bug is #bug17133, already fixed in dbus 1.7.6, so close this one.
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