Firefox crashes as file selection box appears

Binary package hint: firefox

Whenever I choose File/Open File or attempt to download a file, Firefox flashes the file selection dialog on the screen and immediately crashes. It has only started doing this recently. The crash happens in safe-mode or in normal mode.

I also run KDE 3.

$ lsb_release -rd
Description: Ubuntu 8.04.2
Release: 8.04

Firefox About:
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.8) Gecko/2009032711 Ubuntu/8.04 (hardy) Firefox/3.0.8

$ apt-cache policy firefox
firefox:
  Installed: 3.0.8+nobinonly-0ubuntu0.8.04.2
  Candidate: 3.0.8+nobinonly-0ubuntu0.8.04.2
  Version table:
 *** 3.0.8+nobinonly-0ubuntu0.8.04.2 0
        500 http://au.archive.ubuntu.com hardy-updates/main Packages
        500 http://security.ubuntu.com hardy-security/main Packages
        100 /var/lib/dpkg/status
     3.0~b5+nobinonly-0ubuntu3 0
        500 http://au.archive.ubuntu.com hardy/main Packages

Here are some tracebacks running in safe mode with gdb:

pfl@Jodie:~$ gdb /usr/lib/firefox-3.0.8/firefox
GNU gdb 6.8-debian
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "i486-linux-gnu"...
(no debugging symbols found)
(gdb) r -safe-mode
Starting program: /usr/lib/firefox-3.0.8/firefox -safe-mode
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[Thread debugging using libthread_db enabled]
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[New Thread 0xb7c636c0 (LWP 12613)]
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---Type <return> to continue, or q <return> to quit---
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[New Thread 0xb5c54b90 (LWP 12616)]
[New Thread 0xb5453b90 (LWP 12617)]
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---Type <return> to continue, or q <return> to quit---
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[New Thread 0xb49f8b90 (LWP 12618)]
[Thread 0xb49f8b90 (LWP 12618) exited]
[New Thread 0xb41f7b90 (LWP 12619)]
[Thread 0xb41f7b90 (LWP 12619) exited]
[New Thread 0xb41f7b90 (LWP 12620)]
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[New Thread 0xb24c3b90 (LWP 12622)]
[New Thread 0xb49f8b90 (LWP 12621)]
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[New Thread 0xb1cc2b90 (LWP 12623)]
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[New Thread 0xb137fb90 (LWP 12624)]
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[New Thread 0xb0b1ab90 (LWP 12625)]
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[New Thread 0xb02fbb90 (LWP 12627)]

(firefox:12613): GLib-GIO-CRITICAL **: g_simple_async_result_set_from_error: assertion `error != NULL' failed

(firefox:12613): GLib-CRITICAL **: g_error_free: assertion `error != NULL' failed

(firefox:12613): GLib-GIO-CRITICAL **: g_simple_async_result_set_from_error: assertion `error != NULL' failed

(firefox:12613): GLib-GIO-WARNING **: (/build/buildd/glib2.0-2.16.6/gio/gfile.c:5249):IA__g_file_load_partial_contents_finish: runtime check failed: (g_simple_async_result_get_source_tag (simple) == g_file_load_contents_async)

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0xb7c636c0 (LWP 12613)]
0xb615eaa0 in g_file_load_partial_contents_finish () from /usr/lib/libgio-2.0.so.0
(gdb) where
#0 0xb615eaa0 in g_file_load_partial_contents_finish () from /usr/lib/libgio-2.0.so.0
#1 0xb0b2ba75 in ?? () from /usr/lib/gio/modules/libgiohal-volume-monitor.so
#2 0xb6177d63 in g_simple_async_result_complete () from /usr/lib/libgio-2.0.so.0
#3 0xb61617e9 in ?? () from /usr/lib/libgio-2.0.so.0
#4 0xb6177d63 in g_simple_async_result_complete () from /usr/lib/libgio-2.0.so.0
#5 0xb6177db1 in ?? () from /usr/lib/libgio-2.0.so.0
#6 0xb6b2c101 in ?? () from /usr/lib/libglib-2.0.so.0
#7 0xb6b2dcf6 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#8 0xb6b310b3 in ?? () from /usr/lib/libglib-2.0.so.0
#9 0xb6b3166e in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#10 0xb77a1510 in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#11 0xb77b62a8 in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#12 0xb77b6775 in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#13 0xb786611a in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#14 0xb783557a in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#15 0xb77b6460 in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#16 0xb77a18b2 in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#17 0xb6b6200d in ?? () from /usr/lib/libglib-2.0.so.0
#18 0xb6b2dcf6 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#19 0xb6b310b3 in ?? () from /usr/lib/libglib-2.0.so.0
#20 0xb6b31497 in g_main_loop_run () from /usr/lib/libglib-2.0.so.0
#21 0xb673e6f9 in gtk_dialog_run () from /usr/lib/libgtk-x11-2.0.so.0
#22 0xb77aedd4 in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#23 0xb77aa015 in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#24 0xb7872471 in NS_InvokeByIndex_P () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#25 0xb70c0ef7 in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#26 0xb70c6c9d in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#27 0xb7bab30b in js_Invoke () from /usr/lib/xulrunner-1.9.0.8/libmozjs.so
#28 0xb7b9e1cc in ?? () from /usr/lib/xulrunner-1.9.0.8/libmozjs.so
#29 0xb7bab35a in js_Invoke () from /usr/lib/xulrunner-1.9.0.8/libmozjs.so
#30 0xb7bab656 in ?? () from /usr/lib/xulrunner-1.9.0.8/libmozjs.so
#31 0xb7b75e59 in JS_CallFunctionValue () from /usr/lib/xulrunner-1.9.0.8/libmozjs.so
#32 0xb745c1cd in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#33 0xb748def4 in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#34 0xb7378785 in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#35 0xb7378be7 in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#36 0xb738f34f in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#37 0xb738f51a in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#38 0xb738fe16 in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#39 0xb74dc96d in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#40 0xb738f24d in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#41 0xb738fcee in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#42 0xb720c22d in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#43 0xb7313644 in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#44 0xb7866176 in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#45 0xb7835607 in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#46 0xb77b63e2 in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#47 0xb76457f6 in ?? () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#48 0xb70960b0 in XRE_main () from /usr/lib/xulrunner-1.9.0.8/libxul.so
#49 0x08049033 in ?? ()
#50 0xb7c7b450 in __libc_start_main () from /lib/tls/i686/cmov/libc.so.6
---Type <return> to continue, or q <return> to quit---
#51 0x08048cc1 in ?? ()