I have added following lines into php.ini
[XDebug] zend_extension = C:\\PROGRA~1\\PHP5\\ext\\php_xdebug-2.1.0-5.3-vc9.dll xdebug.remote_enable=on xdebug.remo
Its happen because of permission. you have to add the permission of that specific app/user profile from the folder's Properties Security tab.
I use PHP with IIS server so. It worked for me by adding IIS_USER in security permission.