Internet connection - Self-Assigned IP Address - HELP!?

[Fred]

Tell the others to stop messing up your system. If they have assigned an IP address to the router they are disrupting the network. Block their connection to the router by Mac address if they do not stop messing with you. since it is your connection you have every right to insist they do NOT connect other devices without getting a qualified engineer to make sure they do not affect your service. you should NEVER use ANY static IP addresses on ANY machine on a network as it can cause duplicated IP addresses.