We have a user that gets an "IP address conflict error" that pops up on the screen about three times a day. She x's out of the error and then it seems to correct itself. Outlook disconnects and then re-connects momentarily.

I disconnected her data patch cable and ping her IP address and I dont get a response. Plug it back in and I get a response. I would think there would be no conflict if another device doesn't have her same IP address.

Any suggestions?

Fill in her IP stack and see if the issue returns.

There are times when a network snafu completely or partially corrupts your IP installation, which causes your TCP/IP network connection to fail or behave erratically. When this happens, the best solution is to rebuild the TCP/IP protocol stack.

In previous versions of Windows, rebuilding the TCP/IP protocol stack was a simple operation--you just removed and reinstalled TCP/IP. In Windows XP, you can't remove TCP/IP because it's considered an integral part of the operating system.

However, XP does come with a command-line utility--called NetShell--that allows you to reset all TCP/IP-related registry settings to their default values. The end result is essentially the same as installing a brand-new TCP/IP configuration.

To reset all TCP/IP-related registry settings,open a command prompt and type the following command:

netsh int ip reset filename

You must specify a log file in the filename placeholder for this command to work. Details about which registry keys were modified will appear in the log file.

Hope this helps.

I believe the command "netsh winsock reset" will do the same thing.

Does she have a static or dynamic IP address?

On her computer, run ipconfig to find out if it is a static IP address or DHCP address. Then ping the IP address. Then run arp to see who has the IP address. You may need to do this over a period of time, but you should eventually get the MAC address of the other computer using her IP address. Then figure out how there is a conflict (dhcp should handle this without assigning the same address). Probably some device has a static IP address or there is another unauthorized dhcp server on the network.

The PC is using DHCP.
I looked at the arp table and sure enough the IP address in question was listed with the MAC address. I found a IEEE search online via MAC address and the result was "Nortel" as the manufacturer. Our phone system is a Nortel SL1. I pretty sure we will find the IP address assigned to the Nortel in some fashion. When I ping the IP address I dont get a response when her PC is unplugged. The conflict only happens accasionaly.

Thanks for all your help on this.

The Nortel may be set to not reply to pings.

I like to use a freeware called Look@Lan. I can see every device on the network and it's ip address. With some fanangling, you can get the MAC address as well. With her problem occuring sporadically, you could also launch Wireshark(another freeware) and capture packets, etc for a while, then go back and search for that ip address and see what all has it and what responded with it...but you seem to have already figured it out.

I use Colasoft..another freeware network narc. It'll tell just about anything you'd want to know.

I'd find out what the DHCP server is up to in a dynamic environment.

Many implementations will attempt to ping an address (even if it's not associated with a current lease.) before reissuing it.

If her machine is set to DHCP and is working, you might note the MAC in the conflict message, track it down through the switch (if managed), and see if the other machine is set statically. If so, fix that.

Colasoft is exactly what I needed. Very valuable resource. Thanks RBF.