Internet connection issues, where is my default gateway?

[Crazy Jarvis]

So my dad's desktop decided to stop connecting to the internet, upon my inspection and investigating ipconfig in the command prompt I noticed the default gateway entry was blank.
ipconfig/release
ipconfig/renew
didn't fix the issue.

Beneath is the data given by the ipconfig/all :

Microsoft Windows XP [Version 5.1.2600]
© Copyright 1985-2001 Microsoft Corp.

C:\Documents and Settings\User>ipconfig/all

Windows IP Configuration

Host Name . . . . . . . . . . . . : computer
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Unknown
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter Local Area Connection 2:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : NVIDIA nForce 10/100/1000 Mbps Ether
net
Physical Address. . . . . . . . . : 00-15-F2-89-1A-D6
Dhcp Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Autoconfiguration IP Address. . . : 169.254.222.90
Subnet Mask . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . :

C:\Documents and Settings\User>
Sorry, I forgot to mention - it is connected via ethernet cable straight into the router.
We have 2 other computers in the household on wireless connectivity which work fine. The router isn't the issue. (We're using a BT homehub)
When putting a wireless modem on the computer it still picks up the connection as before (Limited or no connectivity) but remains Default Gateway-less.
Hi efflandt as said previously with a wireless modem connected (Ruling out the ethernet cable issue) we had the same response from cmd. We have also tried 2 other ethernet cables.
I have since ran some software to reset winsock stuff. That didn't work either, currently running a virus scan and next I'll take down the firewalls and see if they're stopping it connecting.