Error establishing a database connection (again)

This has been happening more and more frequently. It only seems to be my WordPress profile. IPB, SMF forums are not affected and also a moveable type blog are all on the same shared server using mySql.

Error is:

Error establishing a database connection

This either means that the username and password information in your wp-config.php file is incorrect or we can’t contact the database server at localhost. This could mean your host’s database server is down

After upgrading to 2.1, I’ve encountered the same message over and over again any time I try to login or access the blog at all. Everything else on the site works, except for the WordPress database. My host tells me everything is fine with my account, but they’re checking again.

I’m having this very same issue but with 1.5, suddenly after 1 years…
When I connect with phpmyadmin to the database it gives me this error when choosing “operations”

The additional Features for working with linked Tables have been
deactivated. To find out why click here.

Don’t know if it’s related…

Not really sure how this happens but this is what solved it for me.

I ran the following php to show how mysql was configured for php:

<?php
        // Display a list of PHP?s compile-time features
        phpinfo();
?>

Under the mysql section you’ll see the following showing that PHP is looking for the socket under a /var dir by default:

MySQL Support enabled
Active Persistent Links 0
Active Links 0
Client API version 4.1.22
MYSQL_MODULE_TYPE external
MYSQL_SOCKET /var/mysql/mysql.sock
MYSQL_INCLUDE -I/usr/include/mysql
MYSQL_LIBS -L/usr/lib/mysql -lmysqlclient

You can also run the following to try to make a db connection through PHP and it will show the connection error which points to it looking for the mysql.sock file in the wrong directory.

<?php

if ($cn = mysql_connect("<host>", "<username>", "<password>")) {
echo "connected";
} else {
echo "not connected - " . mysql_error();
}

?>

To solve this I edited the php.ini file for my server and changed:

mysql.default_socket =

to

mysql.default_socket = /tmp/mysql.sock

After searching, searching and searching, this is the only thing I have found that related to my problem. And it worked! Thanks.
I am using XP Pro/Sp2 (I had IIS5.1) Abyss Web Server, PHP 5.2.1, MySql 5 (both Came with Abyss). I still had the same problem with this setup as with ISS. “Error establishing a database connection” I use this server on my home computer for web development.
I fought this thing for two weeks. Somewhere there should be a notice in the downloads, etc., to Windows users about this. PHP was working fine for everything except WordPress. So even though it is a PHP.ini modification required, it is also a WordPress problem for Windows users. And as a plus, a logon script I was using that did not work is now working too.
Again Thank you!