php with user permissions calls cli not cgi on ubuntu

when set to run php scripts with the user's permissions on ubuntu, the cgi wrapper scripts call /usr/bin/php4 instead of /usr/bin/php4-cgi. this causes all php scripts to fail with the log entry:

[Mon Nov 06 21:18:12 2006] [error] [client 192.168.0.1] Premature end of script headers: php4.cgi

, and reporting a 500 internal server error to the browser.