points and boxes - core dump

I am facing an interesting core dump:

action=# select version();
version
-------------------------------------------------------------
PostgreSQL 7.2 on i586-pc-linux-gnu, compiled by GCC 2.95.3
(1 row)

When computing the distance between a point and a box everything seems
to be ok:

action=# select '1,1'::point <-> '2,2,2,2'::box from t_struktur limit 3;

?column?
-----------------
1.4142135623731
1.4142135623731
1.4142135623731
(3 rows)

Let's have a look at the data structure of the table:

action=# \d t_struktur
Table "t_struktur"
Column | Type | Modifiers
--------+--------------------------+-------------------------------------------------------

tstamp | timestamp with time zone | default now()
id | bigint | not null default
nextval('"t_struktur_id_seq"'::text)
koord | box |
typid | bigint |
Indexes: idx_struktur_koord,
idx_struktur_typid
Primary key: t_struktur_pkey
Rules: rule_struktur_del,
rule_struktur_upd

When using the field koord instead of a static box the system will core
dump:

action=# select '1,1'::point <-> koord from t_struktur limit 3;
server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
The connection to the server was lost. Attempting reset: Failed.
!#

These are the first three records in the table:

action=# SELECT * FROM t_struktur LIMIT 3;
tstamp | id | koord | typid
-------------------------------+----+-------------+-------
2002-05-08 14:30:17.594642+02 | 4 | (1,1),(1,1) | 4
2002-05-07 12:28:07.113876+02 | 2 | (4,3),(2,1) | 4
2002-05-08 14:36:15.152699+02 | 5 | (3,4),(1,2) | 3
(3 rows)

The strangen thing is that using the values directly seems to work
pretty well:

action=# SELECT '1,1'::point <-> '1,1,1,1'::box FROM t_struktur LIMIT 3;

?column?
----------
0
0
0
(3 rows)

action=# SELECT '1,1'::point <-> '4,3,2,1'::box FROM t_struktur LIMIT 3;

?column?
----------
1
1
1
(3 rows)

action=# SELECT '1,1'::point <-> '3,4,1,2'::box FROM t_struktur LIMIT 3;

?column?
----------
1
1
1
(3 rows)

Does anybody have an idea why the problem occurs?

Hans