I also experienced hangs when starting Evolution after upgrading glib
with friends from experimental. The hang happened every time, and
occured when the graphics of the UI was partly displayed.
Attached is the strace. I suspected glib to be the problem, so I
downgraded to the version from unstable (and had to downgrade
libgnomevfs and pango too). This solved the problem. Unfortunately, the
hang did not resurface when I upgraded to experimental glib++ again.
What is the most useful way to investigate it if it happens again? Debug
symbols for glib and gnomevfs turned on?