I am running PHP 5.3.3, with Apache 2.0 Handler and MySql Server 5.1. My OS is Vista Home Premium 32 bit with SP2. MySql works fine from the command prompt, Apache is running and PHP works. But I cannot access the mysqli classes. This simple program: <?php $mysqli = new mysqli("localhost", "root", "######", "testDB"); #I've deliberately obliterated the password if (mysqli_connect_errno()) { printf("Connect failed: %s\n", mysqli_connect_error()); exit(); } else { printf("Host information: %s\n", mysqli_get_host_info($mysqli)); } ?> produces this error message: Warning: mysqli::mysqli() [mysqli.mysqli]: [2002] A connection attempt failed because the connected party did not (trying to connect via tcp://localhost:3306) in C:\Apache\htdocs\mysqlconnect.php on line 3 Warning: mysqli::mysqli() [mysqli.mysqli]: (HY000/2002): A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. in C:\Apache\htdocs\mysqlconnect.php on line 3 Fatal error: Maximum execution time of 30 seconds exceeded in C:\Apache\htdocs\mysqlconnect.php on line 3 I guess PHP cannot find the mysqli classes. I've checked the phpinfo() output and discovered : Configuration File (php.ini) Path C:\Windows Loaded Configuration File C:\PHP\php.ini I don't know if this ok. I've tried changing the location of the loaded file to C:\Windows\php.ini, but to no avail, and I don't know how to change the location of the config file. I am obviously doing something wrong, but I don't know what. Can anyone help? Ironically, everything worked perfectly before I upgraded to PHP 5.3.3!