There are two issues here:

• For MySQL, connecting to "localhost" means using a Unix socket (or a named pipe in Windows). That's why you needed to set $ENV{'MYSQL_UNIX_PORT'}. Instead of doing that, you could have used either of these statements:
  

  • my $dbh=DBI->connect('dbi:mysql:dbname'
            . ';host=127.0.0.1'
            . ';port=3310',
    'user', 'password');
    [download]

  • my $dbh=DBI->connect('dbi:mysql:dbname'
            . ';host=localhost'
            . ';mysql_socket=/var/mysql4.1.9/mysql.sock',
    'user', 'password');
    [download]

• As for the client issue, with MySQL 4.1 there is a new communication protocol to identify clients to the server. Also here, you have two choices:
  • Reinstall DBD::mysql, using the new client libraries from the newly installed 4.1.9 package.
  • Ask the administrator to change your password using the OLD_PASSWORD function, or do it yourself: just connect to the server using the command line client, and issue this command:

    SET PASSWORD=OLD_PASSWORD('yoursecretpassword');
    [download]

HTH