CGI-PHP error and Redirection Issue WordPress MU

Solution:1

You need to fix your php.ini

Add/fix this line:

force_cgi_redirect = 0

or, in latest PHP versions:

cgi.force_redirect = 0

Solution:2

From http://us3.php.net/security.cgi-bin

PHP CGI with VirtualHosts.

This is what I found out while trying to get php to work as CGI with Apache VirtualHosts.

By enabling 'force-cgiredirects', you *must*:
1) set 'cgi.fix_pathinfo=1' in php.ini
2) leave doc_root commented out (php.ini also)

If you miss item 1, the apache logs will show 'unexpected T_STRING' in the php binary.
If you miss item 2, you'll only see 'No input file specified.', instead of the expected output.

You can then turn on the php support for a particular vhost by defining:

Action php-script /cgi-bin/php

inside the corresponding <VirtualHost> directive.