Home network connectivity problem - reposted

[daz]

Two PC's behind a Netgear Firewall Router . Both can access the Internet. Both can access each others shared folders. Both can ping the firewall and themselves. One running 2000 Professional SP4 the other XP Professional SP2.
The one running 2000 can ping XP but XP can't ping 2000 - "Request timed out"

2000 Pro:

IP: 192.168.0.2
Mask: 255.255.255.0
Gateway: 192.168.0.1

XP Pro:

IP: 192.168.0.4
Mask: 255.255.255.0
Gateway: 192.168.0.1

(I have another machine running 2000 Pro on 192.168.0.3)

Both machines are in the same workgroup called workgroup. The windows personal firewall on XP machine is turned off.

Any thoughts gratefully received.