To reset tcpip in the registry
netsh int ip reset resetlog.txt

Windows 2000
Boot to safe mode
Remove TCPIP
Reboot
Export Winsock and Winsock2 keys
Reinstall TCP/IP

Windows XP Home or Professional
Unable to Automatically obtain an IP Address or I get an IP Addess of 169.254.x.x and I know DHCP Server is running somewhere on the network
Start
Run
notepad c:\windows\inf\nettcpip.inf
Control H
Find 0xA0
Replace with 0x80
Replace All
Save and exit notepad
Control Panel
Network connections
Lan properties
Install
Protocol
Have disk
c:\windows\inf
TCP/IP (not tcpip v6)
Highlight Internet Protocol TCP/IP
Uninstall
Reboot
(After reboot) Start
Run
Regedit
My Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services (Not CurrentControlSet001 or 2 or 3)
Highlight Winsock
Delete key
Highlight Winsock2
Delete key
Close regedit
Control Panel
Network connections
Lan properties
Install
Protocol
Internet Protocol TCP/IP
Reboot
Fixed
When you are prompted to confirm the deletion, click Yes.