LIBPQ: program crashed during executing query

Hi!

My C program executes a pretty complex query (of length about 600 chars,
with subqueries, etc.).
When I run it (on Linux), it crashes with "Segmentation fault (core
dumped)".
I'm sure that the program crashes on this specific PQexec command.

Is there a length limit for queries in PQexec, or is there any other reason
for it?
The query is attached.

Thanks in advance,

Alex

P.S. The query is:
SELECT s1.GivingCode FROM Scored s1, Scored s2
WHERE s1.Score >= 8 AND s2.Score >= 8 AND s1.Year = s2.Year AND
s1.GivingCode = s2.ReceivingCode AND s1.ReceivingCode = s2.GivingCode AND
s1.GivingCode NOT IN (SELECT Code FROM Friends) AND
s1.ReceivingCode IN (SELECT Code FROM Friends) AND
NOT EXISTS (SELECT * FROM Represented re1, Represented re2, Scored sc
WHERE
re1.Year = re2.Year AND re1.Year = sc.Year AND re1.Code = s1.GivingCode
AND
re2.Code = s1.ReceivingCode AND
((sc.GivingCode = s1.ReceivingCode AND sc.ReceivingCode = s1.GivingCode
AND sc.Score < 8) OR
(sc.GivingCode = s1.GivingCode AND sc.ReceivingCode = s1.ReceivingCode
AND sc.Score < 8)))