PHP4.0.5 CGI and NS Enterprise

I've just built PHP4.0.5 as a cgi on Solaris 2.6/Netscape Enterprise 3.6 based server. Running a test file through the cgi works fine but as soon as I try to configure the cgi-bin to use it I get an error 500 and the following in my Netscape error logs: [18/May/2001:15:11:01] failure (27298): for host xxx.xxx.xxx.xxx trying to GET /cgi-max/php.cgi/myfile.php, cgieng_scan_headers reports: the CGI program /usr/local/phpbuild/php.cgi did not produce a valid header (program terminated without a valid CGI header. Check for core dump or other abnormal termination) Anyone got any clues what the hell is going on? Thanks Max