IP address connect problems

Problem Connecting.
"Another device on the network is using your computers IP address ( numbers here)(***.***.*.**)
Try connecting again later. If you continue to have problems, change the IP address of this computer or the IP address of the other device. Contact the network administrator if you nee more information."

I get this message every so often on one of my MacBook Pros, more on one than the other.
What can I do to stop this from Happening? I turn off my Mac router and back on that fixes it but I don't want to do this every time I wake my computer.

Please help me if you can. Thanks.
MacBook Pro 15 in. *OS X 10.8.2,*NVIDIA GeForce 9400M 256 MB

Set up using WPA2-Personal and not WEP?

Thanks I believe I already have this set.

Make sure your router is setup to use DHCP. Also check your network settings in System Preferences Network, again to make sure you're using DHCP. (click on the TCP/IP tab to check)

That is set up.
Below is an answer I got else where.

"It's not a sign there is any issue with your laptop.
Since this issue has been with us for over a decade.
[This I don't know how to do.]

Did you try changing the Wireless DHCP address reservation, range (that's in the router by the way)
[I also don't know how to do this.]or tell your apple laptop to forget this network and do over (on the laptop?)
We got this problem because of a battle long ago over network protocols. As our government paid for the work, it was free for all to use, WARTS AND ALL. So it's all about the money and some folk don't want to know that this is a good system but far from perfect.
this issue has been with us for over a decade"
This was a reply from MacNN.