Cannot ping other computers in workgroup. Wireless Network is connected. What's wrong? Help!?

Have 2 comps on workgroup working fine. Want to add another. Turned off firewall, added to workgroup, but when view network it only shows me one (the one I'm trying to add) computer. My other computers are working okay on the network. The only difference I can see is that the wireless connection is not strong.

Cannot ping other computers in workgroup. Wireless Network is connected. What's wrong? Help!?vista

First, log into your router from any of the computers and check the DHCP table to see what clients are connected.

Assuming that at least two are, get the IP addresses of both and try pinging them.

Is it possible that somehow your other computers are on a different subnet?

Cannot ping other computers in workgroup. Wireless Network is connected. What's wrong? Help!?antispyware

uninstall the network card drivers and install it again...also please check whether any virus has affected ur system....
Is the new PC you have added getting an ip address assigned from your router/access point?

From Start | Accessories, open the 'Command Prompt'. At the resulting prompt, enter 'ipconfig', and press enter key.

You should see a list of the network adaptors on the system, and underneath each entry the current IP address, subnet mask and default gateway.