Bug#635174: Here Too!

[Tsu Jan]

After a series of updates with synaptic, exactly the same thing happened 
to me with gnome-shell-3.0.2-1 from experimental. I became suspicious 
about the new gjs, downgraded it from 1.29.0-1 to 0.7.14-1, and the 
problem was fixed. The relevant lines in .xsession-errors might be:

x-session-manager[3505]: WARNING: App 'gnome-shell.desktop' respawning 
too quickly
gnome-shell-calendar-server[3661]: Got HUP on stdin - exiting