Confusing PDO-only problem : Can't connect through socket/Access denied/Can't connect to server (shared host)

Question

So the problem changed from what it was, i\'ll leave the original question below to prevent bad reviews on answers like I had after someone editing his question I answered :

Answer 1

Can you try 127.0.0.1 as the server name instead of localhost?

IIRC, with some mySQL drivers / adapters, this decides whether the socket is used for establishing the connection or not.