Wireless won't connect to the Internet

(from a JohnWill post)

IP addresses of 0.0.0.0 are normally caused by one of the following.

Diagnosis:
1. DHCP Service not running.
2. Duplicate IP address on the network.
3. Bad NIC card drivers.
4. Defective NIC hardware.

Resolution:
1. Check Control Panel, Administrative Tools, Services. The DHCP Client service should be Started and its Startup Type should be Automatic.
2. Turn off ALL of the computers and other network connected devices, reboot the router, then restart all the computers and other network devices.
3. Check for upgraded drivers and/or reload the Network drivers.
4. Replace the Network Interface Card.

There has also been at least one case where switching from using Dell WLAN to XP’s WZC resolved the issue.