I'm presuming this bug is something in the underlying gtk code, because the following all hang on startup without displaying any graphics:
gdm gnome-terminal gaim xchat gnome-session strace doesn't show anything obviously relevant, leading me to believe the problem is in library code. An instrumented gdm shows the hang happening somewhere in gtk_init(). This only started when I dist-upgraded yesterday. I'm not sure which packages are relevant here, but gtk+2.0 is 2.4.1-4 and libgnome2-0 is 2.6.1-2. In the interests of getting work done, I'd like to downgrade back to GNOME 2.4, but it's such a huge maze of twisty dependencies, all alike, that I'm not sure how to go about it. Suggestions are welcome. Also, see David Mosberger's post to debian-ia64 about this same problem. -=Eric

