Error start the server

[NavaTux]

Eshell V5.6.5  (abort with ^G)
(nitrogen@REDACTED)1> Recompile: ./src/pages/web_index

i use nitrogen framework,whenever i started my web app,http://
localhost:8000
the error shows the follwed one:
what does it mean elaborately?
what is the solution?
how to identify the errors easily ??#generic question


=ERROR REPORT==== 23-Mar-2010::22:05:02 ===
Failed initiating web server:
undefined
{{listen,eaddrinuse},
 {child,undefined,
        {httpd_acceptor,{0,0,0,0},8000},
        {httpd_acceptor,start_link,
                        [<0.69.0>,ip_comm,
                         {0,0,0,0},
                         8000,httpd_conf__0_0_0_0__8000,15000]},
        permanent,1000,worker,
        [httpd_acceptor]}}


=INFO REPORT==== 23-Mar-2010::22:05:02 ===
    application: navatest
    exited: {shutdown,{navatest_app,start,[normal,[]]}}
    type: temporary