My xscreensaver-demo crashed:

gdb /usr/bin/xscreensaver-demo core

db) bt
#0  0xb7776424 in __kernel_vsyscall ()
#1  0xb6ad6651 in raise () from /lib/tls/i686/cmov/libc.so.6
#2  0xb6ad9a82 in abort () from /lib/tls/i686/cmov/libc.so.6
#3  0xb6b0d49d in ?? () from /lib/tls/i686/cmov/libc.so.6
#4  0xb6b17591 in ?? () from /lib/tls/i686/cmov/libc.so.6
#5  0xb6b1a710 in ?? () from /lib/tls/i686/cmov/libc.so.6
#6  0xb6b1bf9c in malloc () from /lib/tls/i686/cmov/libc.so.6
#7  0xb6b1f4b0 in strdup () from /lib/tls/i686/cmov/libc.so.6
#8  0x0804ecd5 in make_hack_name ()
#9  0x0804ee6e in format_hack ()
#10 0x0804f98f in write_init_file ()
#11 0x08057220 in ?? ()
#12 0x0805b1d1 in ?? ()
#13 0x0805b9d2 in pref_changed_cb ()
#14 0xb6ee6dcc in g_cclosure_marshal_VOID__VOID ()
   from /usr/lib/libgobject-2.0.so.0
#15 0xb6ed9252 in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
#16 0xb6eed99d in ?? () from /usr/lib/libgobject-2.0.so.0
#17 0xb73e5ac2 in ?? () from /usr/lib/libgtk-x11-2.0.so.0
#18 0xb73e607f in ?? () from /usr/lib/libgtk-x11-2.0.so.0
#19 0xb73e6302 in ?? () from /usr/lib/libgtk-x11-2.0.so.0
#20 0xb73e643f in gtk_bindings_activate_event ()
   from /usr/lib/libgtk-x11-2.0.so.0
---Type <return> to continue, or q <return> to quit---
#21 0xb74314a7 in ?? () from /usr/lib/libgtk-x11-2.0.so.0
#22 0xb74ae434 in ?? () from /usr/lib/libgtk-x11-2.0.so.0
#23 0xb6ed78b9 in ?? () from /usr/lib/libgobject-2.0.so.0
#24 0xb6ed9178 in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
#25 0xb6eed5e6 in ?? () from /usr/lib/libgobject-2.0.so.0
#26 0xb6eeec33 in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
#27 0xb6eef256 in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
#28 0xb75db646 in ?? () from /usr/lib/libgtk-x11-2.0.so.0
#29 0xb75ed5af in gtk_window_propagate_key_event ()
   from /usr/lib/libgtk-x11-2.0.so.0
#30 0xb75f08cc in ?? () from /usr/lib/libgtk-x11-2.0.so.0
#31 0xb74ae434 in ?? () from /usr/lib/libgtk-x11-2.0.so.0
#32 0xb6ed78b9 in ?? () from /usr/lib/libgobject-2.0.so.0
#33 0xb6ed9252 in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
#34 0xb6eed5e6 in ?? () from /usr/lib/libgobject-2.0.so.0
#35 0xb6eeec33 in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
#36 0xb6eef256 in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
#37 0xb75db646 in ?? () from /usr/lib/libgtk-x11-2.0.so.0
#38 0xb74a6b43 in gtk_propagate_event () from /usr/lib/libgtk-x11-2.0.so.0
#39 0xb74a7e17 in gtk_main_do_event () from /usr/lib/libgtk-x11-2.0.so.0
#40 0xb720539a in ?? () from /usr/lib/libgdk-x11-2.0.so.0
#41 0xb6e2a5e5 in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#42 0xb6e2e2d8 in ?? () from /lib/libglib-2.0.so.0
---Type <return> to continue, or q <return> to quit---
#43 0xb6e2e817 in g_main_loop_run () from /lib/libglib-2.0.so.0
#44 0xb74a83d9 in gtk_main () from /usr/lib/libgtk-x11-2.0.so.0
#45 0x0805e4ad in main ()
(gdb)