Mutoh's will reset the IP address sometimes if the power goes out or something similar. Double check that the IP address on the printer is still what you think it is. The default is 192.168.1.253 which is what it resets back to when it does reset. Also, you can run the command "arp -a" in dos and it will give you a list of every machine in the network. If it's not there and you know for sure that the IP address is set correctly, you probably have a damaged network connector on the printer.