backend process terminates

We've been wrestling with a problem where the backend process terminates
with a SEGSEGV.  We are having a hard time tracking this thing down, so
I decided to run a batch gdb process that single steps through the code
until it crashes and post the output to the list for a request for
assistance.  The problem is that the output file is 324k, so I'm
sticking it on a website so as not to send such a large file as a
attachment.  We would appreciate any assistance folks might have in
helping us determine what is going on here.  The following is the query
run that generated this segfault:

select pcm_getmiles_s('sparta, nc', 'buffalo, ny', 0);

We are building pcm_getmiles_s() into the backend process.

This is Postgresql 7.4.17 on Red Hat Enterprise 4.

The output from the gdb batch process may be found here:

http://www.serioustechnology.com/gdbbatch.txt

Any help will be greatly appreciated.

--
Until later, Geoffrey

Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety.
  - Benjamin Franklin