pthread_testcancel() seems always cause core dump

Hi!
I cvsuped code few days ago. Many application core dump often.
totem, screem and epiphany etc...
I use gdb to trace stack all of them are stop at pthread-testcancel().

$ ls *.core
screem.core totem.core

gdb screem screem.coreGNU gdb 6.1.1 [FreeBSD]
Copyright 2004 Free Software Foundation, Inc.
... ...
Loaded symbols
for /usr/X11R6/lib/gtk-2.0/2.4.0/filesystems/libgnome-vfs.so
Reading symbols from /libexec/ld-elf.so.1...(no debugging symbols
found)...done.Loaded symbols for /libexec/ld-elf.so.1
#0  0x28e4d22b in pthread_testcancel () from /usr/lib/libpthread.so.1
(gdb) q

$ gdb totem totem.core
GNU gdb 6.1.1 [FreeBSD]
... ...Loaded symbols for /usr/X11R6/lib/gstreamer-0.8/libgstelements.so
Reading symbols from /libexec/ld-elf.so.1...done.
Loaded symbols for /libexec/ld-elf.so.1
#0  0x28d9822b in pthread_testcancel () from /usr/lib/libpthread.so.1
(gdb) q