Three computers cant see each other

I have three computers that are on the same network two are wireless one is not. I have disabled all windows firewalls and just uninstalled nortons on the computers. When I ping one from another they arent able to see each other, however when I ping Yahoo from any of them I get results so my connection is good, I am also able to ping the Dlink router as well and get a replay. I am not sure what else to try.

Lost& confused
Thank you