my nginx web unusually show 404 not found why

the web error show

2011/08/12 03:43:28 [error] 23729#0: *1644359 connect() failed (110: Connection timed out) while connecting to upstream, client: ***.***.***.*** , server: _*, request: "GET /iepngfix.htc HTTP/1.1", upstream: "http://xxx.xxx.xxx.xxx:81/iepngfix.htc", host: "xxx.xxx.com"

Please Help me