Do you know if your IP is assigned through DHCP or is it a static IP?
This is not an uncommon problem. Someone using the same IP as you is bringing their machine up on the network. It is probably a machine that isn't used very much or usually isn't connected to the network, which is why you only get the message every once in a while.
every once in a while a system error comes up and says there is a conflict with another i.p on the network. and the the internet goes down. can anyone help me fix this problem?