Doesn't your router dispense the local IP address? That's where the problem is. An internet carrier has nothing to do with local IP addresses unless you are using their router and feel they need to replace it. Devices at times try to establish the same IP address after being turned back on. If the router assigned that number to another device you will get that error message. Reboot of router should fix it.
In addition Starting with Windows Vista even coming out of sleep a computer may report this. There really isn't a conflict, the short answer is Windows is reporting too early that there is a conflict.