We can't do much without a backtrace. Can you try to get one? See http://bugs.php.net/bugs-generating-backtrace.php for instructions.

I got again the latest CVS and compiled it with

./configure --prefix=/etc/httpd \
        --with-apxs=/usr/sbin/apxs \
        --with-config-file-path=/etc/php4/apache \
        --enable-debug=yes \
        --with-exec-dir=/usr/bin \
        --with-system-regex \
        --with-mysql=/usr/local/mysql \
        --with-pgsql=/usr/local/pgsql \
        --with-gd=/usr \
        --with-freetype-dir=/usr\
        --with-zlib \
        --with-ldap \
        --with-imap \
        --enable-track-vars \
        --enable-magic-quotes

and then there was NO segfault, but in the browser appeared (the differences is of course --enable-debug=yes)

BROWSER START
______________________________________________________________________________________________________________________
<br />
<b>Warning</b>:  String is not zero-terminated (ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ?&#204;&#143;*) (source: ./zend_execute.c:449) in <b>/var/www/crm.dir.bg/project.planner.update.php</b> on line <b>38</b><br />
<br />
<b>Warning</b>:  String is not zero-terminated (ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ?&#204;&#143;*
) (source: ./zend_execute.c:449) in <b>/var/www/crm.dir.bg/project.planner.update.php</b> on line <b>38</b><br />
<br />
<b>Warning</b>:  String is not zero-terminated (ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ?&#204;&#143;*@&#193;) (source: ./zend_execute.c:449) in <b>/var/www/crm.dir.bg/project.planner.update.php</b> on line <b>38</b><br />
<br />
<b>Warning</b>:  Cannot add header information - headers already sent by (output started at /var/www/crm.dir.bg/project.planner.update.php:38) in <b>/var/www/crm.dir.bg/project.planner.update.php</b> on line <b>48</b><br />
<br />
<b>Warning</b>:  String is not zero-terminated (ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ?&#204;&#143;*) (source: zend_execute_API.c:274) in <b>Unknown</b> on line <b>0</b><br />
___________________________________________________________________________________________________________________
BROWSER END

and in the error_log
ERROR_LOG START
___________________________________________________________________________________________________________________

[Tue Mar 26 21:22:52 2002] [error] NOTICE:  Too Many Resources Assigned to project TEST, needed 10, assigned 44.

[Tue Mar 26 21:22:52 2002] [error] NOTICE:  Too Many Resources Assigned to project TEST, needed 10, assigned 44.

/var/www/crm.dir.bg/project.planner.update.php(38) : Warning - String is not zero-terminated (ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ?&#204;&#143;*) (source: ./zend_execute.c:449)
[Tue Mar 26 21:22:52 2002]  Script:  '/var/www/crm.dir.bg/project.planner.update.php'
---------------------------------------
./zend_execute.c(449) : Block 0x08193FD0 status:
zend_variables.c(44) : Actual location (location was relayed)
Beginning:  	Overrun (magic=0x402585E8, expected=0x7312F8DC)
      End:	Unknown
---------------------------------------
[Tue Mar 26 21:22:52 2002] [error] NOTICE:  Too Many Resources Assigned to project TEST, needed 10, assigned 44.

[Tue Mar 26 21:22:52 2002] [error] NOTICE:  Too Many Resources Assigned to project TEST, needed 10, assigned 44.

[Tue Mar 26 21:22:52 2002]  Script:  '/var/www/crm.dir.bg/project.planner.update.php'
---------------------------------------
pgsql.c(237) : Block 0x08194148 status:
Beginning:  	Overrun (magic=0x40258568, expected=0x7312F8DC)
      End:	Unknown
---------------------------------------
/var/www/crm.dir.bg/project.planner.update.php(38) : Warning - String is not zero-terminated (ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ?&#204;&#143;*
) (source: ./zend_execute.c:449)
[Tue Mar 26 21:22:52 2002]  Script:  '/var/www/crm.dir.bg/project.planner.update.php'
---------------------------------------
./zend_execute.c(449) : Block 0x08194148 status:
zend_variables.c(44) : Actual location (location was relayed)
Beginning:  	Overrun (magic=0x402586F8, expected=0x7312F8DC)
      End:	Unknown
---------------------------------------
[Tue Mar 26 21:22:52 2002] [error] NOTICE:  Too Many Resources Assigned to project TEST, needed 10, assigned 44.

[Tue Mar 26 21:22:52 2002]  Script:  '/var/www/crm.dir.bg/project.planner.update.php'
---------------------------------------
pgsql.c(237) : Block 0x08194148 status:
Beginning:  	Overrun (magic=0x40258568, expected=0x7312F8DC)
      End:	Unknown
---------------------------------------
[Tue Mar 26 21:22:52 2002] [error] NOTICE:  Too Many Resources Assigned to project TEST, needed 10, assigned 44.

[Tue Mar 26 21:22:52 2002]  Script:  '/var/www/crm.dir.bg/project.planner.update.php'
---------------------------------------
zend_execute_API.c(274) : Block 0x08194148 status:
zend_variables.c(44) : Actual location (location was relayed)
Beginning:  	Overrun (magic=0x402586F8, expected=0x7312F8DC)
      End:	Unknown
---------------------------------------
/var/www/crm.dir.bg/project.planner.update.php(38) : Warning - String is not zero-terminated (ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ?&#204;&#143;*@&#193;) (source: ./zend_execute.c:449)
[Tue Mar 26 21:22:52 2002]  Script:  '/var/www/crm.dir.bg/project.planner.update.php'
---------------------------------------
./zend_execute.c(449) : Block 0x08194148 status:
zend_variables.c(44) : Actual location (location was relayed)
Beginning:  	Overrun (magic=0x402586F8, expected=0x7312F8DC)
      End:	Unknown
---------------------------------------
[Tue Mar 26 21:22:52 2002] [error] NOTICE:  Too Many Resources Assigned to project TEST, needed 10, assigned 44.

[Tue Mar 26 21:22:52 2002] [error] NOTICE:  Too Many Resources Assigned to project TEST, needed 10, assigned 44.

[Tue Mar 26 21:22:52 2002]  Script:  '/var/www/crm.dir.bg/project.planner.update.php'
---------------------------------------
pgsql.c(237) : Block 0x08193EC8 status:
Beginning:  	Overrun (magic=0x40258568, expected=0x7312F8DC)
      End:	Unknown
---------------------------------------
/var/www/crm.dir.bg/project.planner.update.php(48) : Warning - Cannot add header information - headers already sent by (output started at /var/www/crm.dir.bg/project.planner.update.php:38)
[Tue Mar 26 21:22:52 2002]  Script:  '/var/www/crm.dir.bg/project.planner.update.php'
---------------------------------------
pgsql.c(380) : Block 0x08193EC8 status:
Beginning:  	Overrun (magic=0x40258760, expected=0x7312F8DC)
      End:	Unknown
---------------------------------------
Unknown(0) : Warning - String is not zero-terminated (ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ?&#204;&#143;*) (source: zend_execute_API.c:274)
[Tue Mar 26 21:22:52 2002]  Script:  '/var/www/crm.dir.bg/project.planner.update.php'
---------------------------------------
zend_execute_API.c(274) : Block 0x08193EC8 status:
zend_variables.c(44) : Actual location (location was relayed)
Beginning:  	Overrun (magic=0x40258760, expected=0x7312F8DC)
      End:	Unknown
---------------------------------------
___________________________________________________________________________________________________________________
ERROR_LOG END



I hope it is clear, if there is something else I can do please tell me!

P.S. the view in the browser (probably in the error_log) is somehow different on different cases, but I suspect it's from the query and the number of notices from the postgresql server. The lines that are [error] NOTICE: are actually the messages from the postgre.

reclassified

Is your backend(PostgreSQL Server) and libpq matches? 
(i.e. Do you use libpq version that comes with your PostgreSQL Server?)

If version does not match, use the same versoin.

If you still have problem, please send backtrace. I'll fix it.

I use PostgreSQL 7.2 wich I've installed in /usr/local/pgsql (on clear, first I did was rm -r -f /usr/local/pgsql, and also there is no postgre packages from the distribution installed) there are no other postgresql files on my disk, also I've compiled with it --with-pgsql=/usr/local/pgsql, so I suppose I don't use different versions.
If there is a more precise way of discovering this kind of error please tell me (in phpinfo() i didn't find such info).
And as I said when I compile PHP with debug support (--enable-debug=yes) it does not generate SegFaullts only this messages which I posted before, so couldn't make a backtrace.
_______________________________________________
by the way here is the part of the code that is important for the error:

if ($oid == 0) {
	@pg_query($db_conn, "UPDATE resource SET project = NULL, resource = NULL WHERE \"user\" = '$user' AND date = '$date' AND num = '$num'");
}else{
	@pg_query($db_conn, "UPDATE resource SET project = pr.project, resource = pr.resource FROM project_resource as pr WHERE pr.oid = '$oid' AND \"user\" = '$user' AND date = '$date' AND num = '$num'");
}
$tmpn = pg_last_notice($db_conn);


every update actually updates only one row (since user,date,num is primary key), on which a trigger generate this notice

Ok. I'll have look.

This bug has been fixed in CVS.

Thanks for reporting.
Fix will be available in 4.2.0, also.