error in server

[smathaven]

My web and mail sever was setup last year and working properly until recently. I have noticed the following error in the mail log:

1. Courierpop3login:authentication error: input/output error
2. freshclam: getpetch: cant download daily-7199cdiff from database.clamav.net
3. sshd[32097]: invalid user guest for user root
4. postfix/smtpd[11414]:lost connection after CONNECT from localhost[127.0.0.1]
5. postfix/local[11304]: warningipe-command-read: read time limit exceeded
6. high mem -empty, lowmem reserve low, swap pages,...


Can you please help me? I dont know where to start?
shalini

[falko]

What are the outputs of

top

and

df -h

? Maybe your RAM or your hard drive are full...