[otrs] Database connection problem

Hi, I have installed OTRS 2.0.4 on a Fedora Core 3. I have an error message "Can't connect to database" (Can't connect to local MySQL server trough socket '/var/lib/mysql/mysql.soc'. I have this message at the third step when using the web installer (Chapter3: Installation of OTRS framework, pp: 25, on the OTRS documentation) Has anyone an answer for me? Another question is: I have OTRS 1.3 istalled on another server (Fedora Core 3). The connection is very slow: when connecting, when sending an email, when open a ticket. Sometimes we have to wait 2-3 minutes for a ticket to open. Have you any idea? The sql data base has 300Mo. The server has enough freespace and 512 Mo Ram. Any help will be appreciate. Thanks. Alina.