Question: I bought a new desktop PC (eMachine ET1331G-03W from WalMart) with windows 7 installed, but I can not access internet by connecting to my existing wireless router(LinkSys BEFW11S4) with wired cable. Though all other existing desktops and laptops have no problem connecting to the same router. However, the new desktop PC works fine and able to connect to internet if I bypass the router and directly hook up with the cable modem.

At new PC when connecting to the router, I got the below information by typing ipconfig, the IP address looks wrong to me:

autoconfiguration IPv4 Address: 169.254.71.140
subnet mask: 255.255.0.0
default gateway: (empty)
NetBIOS over Tcpip: Enabled

Typing ipconfig at all other desktop and laptop have values like below, which are good to me:

```
    Connection-specific DNS Suffix  . :
    IP Address. . . . . . . . . . . . : 192.168.1.140
    Subnet Mask . . . . . . . . . . . : 255.255.255.0
    Default Gateway . . . . . . . . . : 192.168.1.1

```

The wireless router was on 192.168.1.1, I do not know why the new desktop got 169.254.71.140 IP? It should have something like 192.168.1.xxx, and it was configured to automatically get IP by DHCP.

I have tried to switch cables,power off cable modem, router and reboot new pc many times and got no luck. So I believe this is only an issue related to router or new pc configuration.

Can someone help me figure out the issue?

Answer: 
Does your router give IP-addresses based on MAC-address? The new PC's MAC is not registered in the router therefore it does not get a real IP.
Here is what I would try to do to remedy this problem before calling it a hardware issue and buying a new network card.

1. Try multiple CAT5 cables and different ports (you have done this)
2. Try ipconfig /release, ipconfig /renew at the command line (this is same is repairing)
3. Set a static IP
4. Reinstall the network card drivers (by uninstalling the card and restarting the comp to force the card to be reinstalled - very simple and safe)

ARe you using XP, Vista, Seven? I will post instructions for setting static IP

EDIT ok after re-reading the question I see that you are using Seven..standby for more...

EDIT - instructions are easily on Google for setting a static in SEven. Just be sure to set settings that are relevant to your routers configurations. This can be done by looking at ipconfig /all on one of your other machines.

[Here](http://blog.mclaughlinsoftware.com/2009/11/26/windows-7-static-ip/) are some freshly Googled instructions.

last edit - if all of this fails, uninstall the network card. This is totally safe and will be reinstalled at restart. The card can be uninstalled by expanding the view in [device manager](http://www.techtalkz.com/windows-7/515982-how-use-device-manager-windows-7-a.html), right clicking on the card, and selecting uninstall. Once this is done, restart the machine.