Weird IP error.

Question

Anyone know why this message pops up occasionally? It doesn't seem to harm my internet connection or any of my wireless devices. Although, apple tv tends to disconnect from time to time and it's a pain.
http://i54.photobucket.com/albums/g109/Bonesone4/Picture1-9.png

Answer 1

It's not likely to be a machine that's out-of-range because that would prevent the machine from getting online.
The issue is more than there are two machines trying to use the same IP address - in this case 192.168.1.2
By definition, every IP address has to be unique on each LAN. You cannot have two machines with the address 192.168.1.2 and your machine is telling you that it's detected some other device using the same address.
This is fairly uncommon on DHCP-based networks (the DHCP server takes care of tracking who has which IP address), but if you're using static/manual addressing (where you define the address for each machine) it can happen.
I don't mean to scare you, but it can also happen if someone is piggy-backing onto your wireless network.
The solution is to look at every device you expect to be on the network and check its MAC address (the 6 hex numbers in the message) to find which one is the culprit. You mention AppleTV, so check address. Check also any printers, base stations, iPhones, PS3s, XBoxes, etc.
Ideally everything should be using DHCP (with the possible exception of the base station). If you check every device and don't find one with that MAC address then you have a rogue user on your network and you need to secure your connection.