Pop3d Authentication Erros

my mail server stops authenticating users. When they try to check messages they get the login screen in their mail clients again and again. I have to go to the server and restart saslauth, mysqld and postfix.

I'm getting the following warning when restarting MySQL:

070403 13:53:09 mysqld started
070403 13:53:09 [Warning] Changed limits: max_open_files: 1024 max_connections: 1014 table_cache: 64
070403 13:53:10 InnoDB: Started; log sequence number 0 43654
/usr/libexec/mysqld: ready for connections.

The file my.cnf show the following:

[mysqld]
log=/tmp/mysql.log
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Default to using old password format for compatibility with mysql 3.x
# clients (those using the mysqlclient10 compatibility package).
old_passwords=1
max_connections=2548

[mysql.server]
user=mysql
basedir=/var/lib
max_connections=2548

[mysqld_safe]
err-log=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

Also, my maillogs is showing these errors:

Apr 3 13:24:47 mail1 pop3d: authentication error: Input/output error
Apr 3 13:30:25 mail1 pop3d: authentication error: Input/output error
Apr 3 13:30:28 mail1 pop3d: authentication error: Input/output error
Apr 3 13:30:29 mail1 pop3d: authentication error: Input/output error

Do I have to increase connections on my.cnf? I think 2548 is enough for the amount of user I have which is less than 100 users.