hi hope you can understand this question and offer advice, i have 2 computers networked together with cable ( not wireless ) if i have my main machine on and someone turns other machine on i get an error message on my taskbar saying another machine is trying to use a different ip address on this network, if i click ok on the message it goes away and both machines access the internet ok, is this a problem or do all networks do it thanks for any advice

The message says that another machine is trying to use a DIFFERENT IP address? That's completely normal. A conflict situation only occurs if two devices on a network are trying to use the SAME address.

Hope that helps