pgbench don't return results on Windows

When I measured performance using "pgbench -S" on Windows, I
encounterd the problem that pgbench have not been returned results.

* My environment
OS: Windows XP Professional Edition
pgsql: compiling at postgresql-8.0.0beta2.tar.gz by MinGW
(MD5: ec8d40686b08b902a0db308333f52e47)

* postgresql.conf
max_connection=128
shared_buffers=1000

* cmd.exe
> createdb bench
> pgbench -i bench
> pgbench -S -c 128 -t 20 bench
no response...

This problem was reproduced by about 30% of probability.
Is this problem caused by pgbench? or by pgsql server?

Thanks.

--
Yoshiyuki Asaba
y-asaba(at)sra(dot)co(dot)jp