I could use a Windows networking expert

I'm certainly no stranger to computers and networking, but this one's got me stumped. Here's the situation:

I have a cable modem connected to the WAN port of my wireless router. My gaming PC is connected to one of the wired ports. 3 other PCs regularly use the wireless, including my media center PC. Both PCs are running XP SP3.

Because I moved the media center PC to another part of the house, it gets no wireless signal. I ran a 75' CAT6 cable down there and hooked it up.

The media center PC gets an IP address via DHCP but cannot access the Internet.


So here's what I know so far (unless otherwise noted, I'm talking about the media center PC that cannot access the Internet):

• The cable is good and the router works on that port - I hooked up my laptop and XBox in place of the PC and they work fine.
• The NIC passed all hardware and loopback tests.
• I have the latest drivers for the NIC installed.
• I disabled the wireless adapter.
• I see packets being sent but zero received.
• It cannot ping the router, or any other PC on the network.
• No other PC on the network can ping it.
• The IP address it's getting via DHCP is on the correct subnet and looks right - i.e. the last number is one more than the other devices currently connected.
• I have tried several different ports on the router for giggles.
• I ran the Winsock Fix program that is supposed to fix this sort of problem, and it did not.
• It can access the Internet via wireless if I shlep my router and modem down there.
• It does not show up in the router's list of attached devices. I do see my gaming PC and my wife's EEPC currently connected.

So where do I look next?

Thanks for any advice,

-Joe

Was the loopback test performed with a wrap plug? If not then just the internal loopback was performed which only indicates the protocol stack is in place. My next step would be to give it a static IP address and connect it directly to another pc with a static address on the same subnet. Then try pinging each from the other. If one is old, a direct connection may require a crossover cable or both could be connected to a small hub/switch. If this fails, I'd say the NIC was bad. Hope this helps.

Do you have Windows Firewall enabled, or some other host-based firewall or antivirus software installed? Perhaps that's blocking your inbound traffic somehow?

I've got the Windows firewall disabled and just running AVG anti-virus. I'll try the two PC thing shortly, if I can get it to work without an xover cable, which I don't have.

-Joe