Unable to see the network, able to see the internet? (XP)

This is truly puzzling. I've been wrestling with an individual laptop that suddenly refuses to see the network, be it via Network Places, ping, whatever. However, it is able to access the internet through our gateway without any problems.

I've attempted to reset the TCP/IP stack and uninstall/reinstall the network adapter to no avail.

The strangest symptom? Literally billions of packets in the "Sent" column of the Local Area Network properties. (For instance, it's currently at 803,158,884,809 packets) Immediately you think "Aha... a virus!" But Symantec Antivirus Corporate 8.1 has been installed on this PC all along, and complete system scans with the latest virus definitions discover nothing.

I've tried a system restore to before this problem was occurring, but with no luck.

Any thoughts on what's happening or methods to further diagnose the nature of the problem? Thanks.

What is your gateway? A windows 2000 machine (pro or server)? What services are you running? DHCP or static IPs? Have internet connection sharing enabled on your outgoing NIC card? Running a firewall? You need to give a lot more info here to get something useful out of it.

Gateway is an NT4 server. Running DHCP.

I just determined that putting the gateway/IP/DNS information with a different IP address into the laptop in manually causes it to function again.

I would prefer to return it to DHCP mode, but if this is the only way, so be it.

Any thoughts as to why this might happen? Among the stranger things is that the DHCP service on the server seems to see the laptop when it boots and gets its IP address via DHCP (always the same IP, incedentally), but still can't ping the laptop.