Check your error_log.

All I get is:
[Wed Oct  2 12:16:04 2002] [error] [client 161.225.1.12] Premature end of script headers: /usr/local/share/nagios/cgi-bin//cmd.cgi
 in the http-error.log

If I remove mod_php from the httpd.conf it works fine.
Is there a way to get more info?

Got the same problem after upgrading to mod_php 4.2.3
perl and shell scripts executed as cgi started giving error 500, despite they have been running fine before.
They were running fine from shell.
Disabling mod_php4 in apache httpd.conf restored the normal behavior.
We had to roll back the upgrade.
Please let us know when this will be fixed
Other info: FreeBSD 4.7, apache 1.3.27
Hope this helps others...
Francoise

This is very likely a problem with your apache configure.
Try using the stock httpd.conf and add the correct PHP related lines.

I dunno... unless something changed in the syntax. 
My cgi's definitely worked before upgrading too. I was messing a cgi based monitoring tool (nagios) a few days before the upgrade. It worked and then it didn't. It took me a few days to notice but the only event between the "working" and "non-working" state was the upgrade.

Does any simple cgi scripts work..like the apache
provided exampe printenv script?

nope, no cgi will work using mod_cgi. perl scripts if run via mod_perl work fine. cgi's via fastCGI kinda work... POSTs fail with an internal server error, GETs work fine

That simple 'printenv' script works (and has always worked) just fine here so I'm pretty sure your configuration is somewhat broken. 

I suggest you try with stock apache httpd.conf and then do a clean install of PHP.

(please add your configure line for PHP here btw)

Here's what I have in config.nice. I'm compiling from the ports collection so I actually pick the options from a dialog and freebsd's make actually does the "configure, make, make install"

'./configure' \
'--with-apxs=/usr/local/sbin/apxs' \
'--with-config-file-path=/usr/local/etc' \
'--enable-versioning' \
'--with-regex=system' \
'--without-gd' \
'--without-mysql' \
'--with-gd=/usr/local' \
'--enable-gd-native-ttf' \
'--with-freetype-dir=/usr/local' \
'--with-jpeg-dir=/usr/local' \
'--with-png-dir=/usr/local' \
'--with-zlib' \
'--with-mysql=/usr/local' \
'--with-ldap=/usr/local' \
'--enable-ftp' \
'--with-curl=/usr/local' \
'--with-gettext=/usr/local' \
'--with-pspell=/usr/local' \
'--with-mcal=/usr/local' \
'--prefix=/usr/local' \

I recompiled php4.2.3 manually with the configure options that I previously posted and I was able to run CGIs. There must be a problem with the FreeBSD port. I'll try to contact the port maintainer/ports mailing list and see what they have to say.