My question is why after this many years is this issue still with us? You can see millions of hits on google so why is Microsoft leaving folk asking this question after a decade?
The topic is well discussed and without much detail about your network, I defer to prior discussions and add my question.
A message came up when I opened my computer saying "Windows has detected an IP address conflict. Another computer on this network has the same IP address as this computer. Contact your network administrator for help resolving this issue. More details are available in the Windows System event log." I have windows 7, Service Pack 1, 64-bit OS, 12GB RAM, 500gb HDD. I couldn't find the Windows System event log.
I left my computer switched on today on Hibernate, when I went out, but the internet connection was switched off at the modem. I returned home opened the computer to find the message, and then I turned the modem back on to contact Cnet.