All TCP Ports Closed

[gm__]

Hi!

I have two pc connected by a cable rj45 , both with windows xp and when
i scan with a portscanner (nmap,superscan) i get the message that
Tcp ports open = 0.
How is it possible?
Firewall disabled and no AntiVirus installed.
When i ping them ,both PC respond , so it means that there's connection.

Thanks in advance!

[sguins]

What type of scanner are you using? What type of scan are you running, a vanilla tcp scan? What type of firewall are you running? Have you run a packet sniffer like etherreal on the machine your scanning to determine whether or not it's receiving the traffic?