Ok, hear is the stack trace from an "unexpectedly destroyed" in the context of returning from a gmail message back to the Inbox index error:

Breakpoint 1, IA__g_logv (log_domain=0xb79e98f4 "Gdk", log_level=G_LOG_LEVEL_CRITICAL, 
    format=0xb783deec "%s: assertion `%s' failed", args1=0xbfb43510 "x���� ��\b") at gmessages.c:396
396	  gboolean was_fatal = (log_level & G_LOG_FLAG_FATAL) != 0;
(gdb) thread apply bt all
(gdb) thread apply all bt

Thread 7 (Thread 0xb67a8b90 (LWP 12544)):
#0  0xb7f83410 in __kernel_vsyscall ()
#1  0xb71e65b7 in *__GI___poll (fds=0xb67a7f98, nfds=2, timeout=65535000)
    at ../sysdeps/unix/sysv/linux/poll.c:87
#2  0xb7dffe5a in PR_Poll () from /usr/local/lib/firefox-3.0pre/libnspr4.so
#3  0x080d0a0c in ?? ()
#4  0x08cbd450 in ?? ()
#5  0x00000002 in ?? ()
#6  0x03e7fc18 in ?? ()
#7  0xb7dfe516 in PR_ExitMonitor () from /usr/local/lib/firefox-3.0pre/libnspr4.so
#8  0x080d137d in ?? ()
#9  0x08cbcf70 in ?? ()
#10 0x00000001 in ?? ()
#11 0xb67a8208 in ?? ()
#12 0xb7eb7ff4 in ?? () from /usr/local/lib/firefox-3.0pre/libxpcom_core.so
#13 0x08cbd7b8 in ?? ()
#14 0x00000001 in ?? ()
#15 0xb67a8218 in ?? ()
#16 0xb7e81dd7 in ?? () from /usr/local/lib/firefox-3.0pre/libxpcom_core.so
#17 0x08cbd7d8 in ?? ()
#18 0x00000000 in ?? ()

Thread 6 (Thread 0xb5f75b90 (LWP 12545)):
#0  0xb7f83410 in __kernel_vsyscall ()
#1  0xb7f73b12 in pthread_cond_timedwait@@GLIBC_2.3.2 () from /usr/local/lib/libpthread.so.0
#2  0xb7dfd3a5 in ?? () from /usr/local/lib/firefox-3.0pre/libnspr4.so
#3  0x08c3497c in ?? ()
#4  0x08c58410 in ?? ()
#5  0xb5f7528c in ?? ()
#6  0xb7f745f5 in __pthread_getspecific (key=93793) at pthread_getspecific.c:27
#7  0xb7dfe194 in PR_WaitCondVar () from /usr/local/lib/firefox-3.0pre/libnspr4.so
#8  0xb7e8646f in ?? () from /usr/local/lib/firefox-3.0pre/libxpcom_core.so
#9  0x08c34978 in ?? ()
#10 0x00051fb9 in ?? ()
#11 0x08c58410 in ?? ()
#12 0xb7eb7ff4 in ?? () from /usr/local/lib/firefox-3.0pre/libxpcom_core.so
#13 0x08e2a420 in ?? ()
#14 0x00000000 in ?? ()

Thread 5 (Thread 0xb4679b90 (LWP 12549)):
#0  0xb7f83410 in __kernel_vsyscall ()
#1  0xb7f737e5 in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/local/lib/libpthread.so.0
#2  0xb7dfe226 in PR_WaitCondVar () from /usr/local/lib/firefox-3.0pre/libnspr4.so
#3  0x088daa5a in ?? ()
#4  0x090aeb18 in ?? ()
#5  0xffffffff in ?? ()
#6  0xb1c8b2f0 in ?? ()
#7  0xb1746cb0 in ?? ()
#8  0x08bff4a8 in ?? ()
#9  0x00000000 in ?? ()

Thread 4 (Thread 0xb4e7ab90 (LWP 12550)):
#0  0xb7f83410 in __kernel_vsyscall ()
#1  0xb7f737e5 in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/local/lib/libpthread.so.0
#2  0xb7dfe226 in PR_WaitCondVar () from /usr/local/lib/firefox-3.0pre/libnspr4.so
#3  0x088c6de3 in ?? ()
#4  0x09290278 in ?? ()
#5  0xffffffff in ?? ()
#6  0x092901dc in ?? ()
#7  0xb7e0cff4 in ?? () from /usr/local/lib/firefox-3.0pre/libnspr4.so
#8  0x092902b8 in ?? ()
#9  0x00000000 in ?? ()

Thread 3 (Thread 0xb2593b90 (LWP 12563)):
#0  0xb7f83410 in __kernel_vsyscall ()
#1  0xb7f737e5 in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/local/lib/libpthread.so.0
#2  0xb7dfe226 in PR_WaitCondVar () from /usr/local/lib/firefox-3.0pre/libnspr4.so
#3  0xb7dfe287 in PR_Wait () from /usr/local/lib/firefox-3.0pre/libnspr4.so
#4  0xb7e812f5 in nsEventQueue::GetEvent () from /usr/local/lib/firefox-3.0pre/libxpcom_core.so
#5  0xb7e8243d in ?? () from /usr/local/lib/firefox-3.0pre/libxpcom_core.so
#6  0x09eb3868 in ?? ()
#7  0x00000001 in ?? ()
#8  0xb2593314 in ?? ()
#9  0x00000000 in ?? ()

Thread 1 (Thread 0xb6eca6d0 (LWP 12543)):
#0  IA__g_logv (log_domain=0xb79e98f4 "Gdk", log_level=G_LOG_LEVEL_CRITICAL, 
    format=0xb783deec "%s: assertion `%s' failed", args1=0xbfb43510 "x���� ��\b") at gmessages.c:396
#1  0xb77ed9b9 in IA__g_log (log_domain=0xb79e98f4 "Gdk", log_level=G_LOG_LEVEL_CRITICAL, 
    format=0xb783deec "%s: assertion `%s' failed") at gmessages.c:517
#2  0xb77edbfc in IA__g_return_if_fail_warning (log_domain=0xb79e98f4 "Gdk", 
    pretty_function=0xb7a0ae78 "gdk_window_set_back_pixmap", expression=0xb7a020b3 "GDK_IS_WINDOW (window)")
    at gmessages.c:532
#3  0xb79de9c2 in IA__gdk_window_set_back_pixmap (window=0x0, pixmap=0x0, parent_relative=0)
    at gdkwindow-x11.c:3059
#4  0x08268ecb in ?? ()
#5  0x00000000 in ?? ()