about error log..

[Winnie]

hi..

when i run "nginx", i got the following error log as below:

2007/08/20 09:30:03 [emerg] 27521#0: bind() to 0.0.0.0:25 failed (98: 
Address already in use)
2007/08/20 09:30:03 [notice] 27521#0: try again to bind() after 500ms
2007/08/20 09:30:03 [emerg] 27521#0: bind() to 0.0.0.0:25 failed (98: 
Address already in use)
2007/08/20 09:30:03 [notice] 27521#0: try again to bind() after 500ms
2007/08/20 09:30:03 [emerg] 27521#0: bind() to 0.0.0.0:25 failed (98: 
Address already in use)
2007/08/20 09:30:03 [notice] 27521#0: try again to bind() after 500ms
2007/08/20 09:30:03 [emerg] 27521#0: bind() to 0.0.0.0:25 failed (98: 
Address already in use)
2007/08/20 09:30:03 [notice] 27521#0: try again to bind() after 500ms
2007/08/20 09:30:03 [emerg] 27521#0: bind() to 0.0.0.0:25 failed (98: 
Address already in use)
2007/08/20 09:30:03 [notice] 27521#0: try again to bind() after 500ms
2007/08/20 09:30:03 [emerg] 27521#0: still could not bind()

here're my nginx.conf as following...what should i do????
thx a lot...
==========================================================
 user nobody;
  worker_processes  1;

  error_log  /var/log/nginx-error.log debug;
events {
    worker_connections  1024;
        multi_accept on;
}

  mail {

      pop3_auth         plain apop ;
      pop3_capabilities "LAST" "TOP" "USER" "PIPELINING" "UIDL";

      smtp_auth         login plain;
      smtp_capabilities  ENHANCEDSTATUSCODES 8BITMIME DSN;
      xclient off;

      server {
          listen               25;
          protocol           smtp;
          timeout            300s;
      }
      server {
          listen     110;
          protocol   pop3;
          proxy      on;
          proxy_pass_error_message  on;
      }
  }