An IP address conflict happens when the same address is assigned to multiple computers or devices that try to co-exist on the internet at the same time.
Check to see if your computer network setup is using a fixed/static IP address or if it uses a dynamic one assigned by DHCP. If you're using a fixed address then you've assigned the same IP address to multiple devices. Or you're using an IP address that you don;'t have the authority to use on the internet.
If your computer connects to the internet thru a router then the computer should in most cases be using DHCP and the router should be configured to assign an IP address. These addresses will be NAT'd which means they will be local to your devices behind the router falling into the locally managed ranges and all external traffic will be using the IP address assigned to the router by your ISP when it connected to the internet.
The thing to be careful about is using the same IP address on two different devices even when you're positive that only one will be used on the internet at any one time. The reason is that when the computer comes onto the internet it will be "registered" with that IP address and it's unique hardware address for some period of time. If you then disconnect, and connect the second device with the same IP address and the time for the first assignment hasn't expired, you'll get an "IP address conflict" error as the new device can't register since the IP address is still known to be associated with the first device.
The simplest solution in almost all cases is to use DHCP whenever and where ever you can. There are places and times this isn't appropriate though, and you have to then carefully manage the assignment of IP addresses manually.
Note too, IP address are ONLY managed by the end user when the fall into the 192.168.x.x and 172.16.x.x address ranges. ALL OTHER IP ADDRESS ARE MANAGED UPSTREAM!
(Yeah, there are other exceptions, but for most people here that's not important.)
