PostgreSQL 7.1.3 hanging problems

I have installed PostgreSQL 7.13 (and cygIPC 1.11) and I am having
problems for executing certain SQL-clauses.
I have an application which generates SQL-clauses dynamically, and I have
noticed that
following clause will for example freeze PostgreSQL.
(I need to stop and start it again in order to get it working again.)
Same clause will work just fine in Oracle with the same tables and data,
so the clause itself should be ok.

select distinct project_dim.c_id, project_fact.c_id from project_dim,
project_fact, time_dim where
project_fact.c_project_dim_c_id=project_dim.c_id and
project_fact.c_time_dim_c_id
in (select time_dim.c_id from time_dim where time_dim.c_time in (select
max(time_dim.c_time)
from time_dim where project_fact.c_project_dim_c_id=project_dim.c_id and
project_fact.c_time_dim_c_id=time_dim.c_id))

The error-message I get to pgAdmin II is:

"An error has occured in pgAdmin II: frmSQLInput.cmdExecute_Click"
Number: -2147467259
Description: Error while executing the query; No response from the backend;
Error while reading the socket."

If I split the SQL-clause to two separated clauses like

1) select distinct project_dim.c_id, project_fact.c_id from project_dim,
project_fact, time_dim where
project_fact.c_project_dim_c_id=project_dim.c_id and
project_fact.c_time_dim_c_id
in (select time_dim.c_id from time_dim)

and

2) select max(time_dim.c_time)
from time_dim where project_fact.c_project_dim_c_id=project_dim.c_id and
project_fact.c_time_dim_c_id=time_dim.c_id

then everythinh will work just fine. Has anybody else noticed similar kind
of problems and
should I try to upgrade my Cygwin to newer version? Where I can I download
the PostgreSQL 7.20 binaries for Cygwin?

Mika