Follow below mentioned commands…
1. In command prompt type: Ping -a IP ADDRESS (By this you will find the name of the PC from which IP address is conflicting)
2. Note: If your network has DHCP enabled so check with your network engineer to trace out IP Address assign to which PC.
3. As mentioned above by aikon type following command.
Go to dos prompt (Command Prompt)
ipconfig /release
ipconfig /renew