Windows – WebApp accessible via localhost but not 127.0.0.1

I have seen this a few times and it is usually caused by an incorrect proxy server configuration. If you can access it via telnet (this would not be going via the proxy) then you have effectively verified that a service of some kind (not necessarily IIS!) is running on that port.

I recommend disabling the auto-detect proxy option if you are using Internet Explorer and are not using a proxy or if you must use a proxy add explicit declarations for exceptions rather than relying on the "Bypass Proxy for Local Addresses" checkbox.

MySQL will try to connect to the unix socket if you tell it to connect to "localhost". If you tell it to connect to 127.0.0.1 you are forcing it to connect to the network socket. So probably you have MySQL configured to only listen to the network socket and not to the file system socket.

What exactly is wrong with your unix socket is hard to tell. But I recommend you to read this page on the MySQL reference guide. This should help you.

UPDATE: Based on the updated question: The parameter "socket" should be something like this: "/var/lib/mysql/mysql.sock". This page in the Reference Manual has some more information.

Here you have the beginning of my /etc/my.cnf file:

[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock

Your file should be similar. Then your problem should be solved. Don't forget to restart the MySQL server before you test it.