I found the problem, I had to change the httpd.conf file to include the following lines before the LoadModule php5_module:
PHPIniDir "C:/wamp/bin/apache/Apache2.2.17/bin/php.ini"
Loadfile "c:/wamp/bin/php/php5.3.5/php5ts.dll"
Loadfile "c:/wamp/bin/php/php5.3.5/libpq.dll"
I found this in the following thread: [
forum.wampserver.com]