I just upgrade the php from 4.1.2 to 4.2.0 and the only problem I encounter is using the mysql_pconnect. It seems like sometimes working and sometimes not. I am connecting to the mySQL database with the following code:

function connectDB() {
	$link = mysql_pconnect("localhost", "abc.com", "12345");

	if (!$link)
		die("Couldn't connect to MYSQL");
	mysql_select_db("product")
		or die("Couldn't open product: ".mysql_error());
	return $link;
}

Sometimes I get an error of "Warning: Host 'localhost.localdomain' is not allowed to connect to this MySQL server in /mnt/home/apache/public_html/data.php on line 3
Couldn't connect to MYSQL"

I don't know why sometimes the host has been altered to localhost.localdomain, but sometimes it works just perfectly fine. I have no problem on the previous version (4.1.2). I have a solution for this now which is setting the host of the user permission to not only with "localhost" but also with "Any". However I wish this bug can be fixed in the future time. Thanks.