DHCP or TCP/IP

I have a home user who is behind a linksys wireless router. Communication between the router and system seem to be fine. But I receive a Tcp/ip and a DHCP error every day.
Error: Your computer was not assigned an address from the network (by the DHCP server)for the network Card with the (mac address)the following error occurred.
the operation was canceled by the user..Your computer will continue to try to obtain an address on its own from the network address (DHCP) server.This error is causing a crash everyday.What should I do?