port shown in nmap but no service is running on this port

I am doing nmap of x.x.x.x there I get many open ports but when I login to that system, there are no ports running and no services are shown on the ports. Please help me explain:

PORT      STATE SERVICE22/tcp    open  ssh25/tcp    open  smtp53/tcp    open  domain80/tcp    open  http81/tcp    open  hosts2-ns82/tcp    open  xfer83/tcp    open  mit-ml-dev110/tcp   open  pop3139/tcp   open  netbios-ssn143/tcp   open  imap443/tcp   open  https445/tcp   open  microsoft-ds587/tcp   open  submission1080/tcp  open  socks1801/tcp  open  msmq2000/tcp  open  cisco-sccp3128/tcp  open  squid-http5000/tcp  open  upnp5060/tcp  open  sip7001/tcp  open  afs3-callback8000/tcp  open  http-alt8080/tcp  open  http-proxy8088/tcp  open  radan-http8090/tcp  open  opsmessaging8888/tcp  open  sun-answerbook9200/tcp  open  wap-wsp10000/tcp open  snet-sensor-mgmt