I don't use apache I use omnihttp, but I'm sure it's the same to set up.
I had this problem, when I first messed around with my server, I found that I had to put in the paths for all the "addons" ( i guess you can say this) anyway, I found a part in the config panel, that you set paths for your server to find the language stuff. Like I got perl 5 and I had to set my path to it. it probably looks like this...
.pl C:\httpd\perl\bin\perl.exe
.php C:\httpd\php\bin\php.exe
*.cgi C:\httpd\perl\bin\perl.exe
or whatever, will you have to set the path to the php.exe. I'm not sure if you said you did that, but I hope this helps