Get back onto the Internet fast if you have TCP/IP woes.
TCP/IP problems can be exceedingly difficult to troubleshoot, and at times they appear to break for no apparent reason. Everything looks like it should be working, but you're not able to connect using the protocols. If you have a broken connection, try the following:
Try automated repair. Right-click on the broken connection in the Network Connections folder and choose Repair.
Run the Network Setup Wizard. It walks you step by step through TCP/IP and network configuration and will correct any errors you may have introduced inadvertently.
Reset your router. If you have a home network, the problem may lie with the router or in the connection between the router and your broadband provider. Follow the directions for resetting the router.
Reset your cable modem or DSL modem. If you have a broadband connection, the problem may lie in the assignment of your IP address by your ISP. Power off your cable modem or DSL modem, unplug its Ethernet cable, and leave it powered off for five minutes. Then restart it. This is also a good time to reset your router. You can also try releasing and renewing after you've turned the connection back on.
Reset TCP/IP to its original configuration. If all else fails, you can try to reset your TCP/IP stack to the same state that it was in when XP was first installed on the computer. Use the NetShell utility [Hack #53]. Issue this command: netsh int ip reset [log_file_name], where log_file_name is the name of a file where the actions taken by NetShell will be recorded.