Intermittent core dumps from flist

Greetings,

Stats:  NMH 0.24
        Red Hat Linux 4.2 with Kernel 2.0.32
        GCC 2.7.2

I am experiencing intermitten core dumps when calling flist like 

      flist +inbox -recurse -noshow 

The core is dropped in my ~/Mail directory.  GDB'ing it revelas that
flist died in __libc_free.

Is there a freely available malloc debugger I can use to track this
bug down?

--[Lance]