Comment 4 for bug 32286

I experience the same error. The problem here is that gnome-panel fails to stop when the user logs out.
Perhaps a line was missed that kills it, or something, but that fact is that it keeps running even after the majority of the GNOME processes have stopped.

I tried killing gnome-panel, and when it started again, most of the applets were unresponsive, and a couple of them, namely the ACPI battery monitoring applet (this is on a laptop) crashed or didn't start.

I now have to reboot to check session changes or anything like that.
This could be considered a serious problem.