in the Connections\PowerMailerConnection.php change the following code:
$PowerMailerConnection = mysql_pconnect($hostname_PowerMailerConnection, $username_PowerMailerConnection, $password_PowerMailerConnection) or trigger_error(mysql_error(),E_USER_ERROR);
to:
$PowerMailerConnection = mysql_connect($hostname_PowerMailerConnection, $username_PowerMailerConnection, $password_PowerMailerConnection) or trigger_error(mysql_error(),E_USER_ERROR);
it may take a little for the existing connection to time out, so it may not take efect for a few hors or more.