Im getting the same problem as the OP
The specified CGI application misbehaved by not returning a complete set of HTTP headers.
as he didnt post what he did to stop this, does anyone else know?
Im on a windows server and do have access to the php.ini file.
I also have this at the bottom of each page, not sure its related :
PHP Warning: PHP Startup: pdf: Unable to initialize module Module compiled with module API=20060613, debug=0, thread-safety=1 PHP compiled with module API=20060613, debug=0, thread-safety=0 These options need to match in Unknown on line 0