Vista - Wireless Networking Problem (Time out of LT that accesses other ne

I have installed a wireless network with passphrase protection using Vista
Home Premium (32-bit). The Desktop PC is a wired connection and I can access
the net from two laptops that had never been networked before. I cannot,
however, access the net from any of three laptops that have previously
accessed other nets even though they can still access those nets. These LTs
detect the net and I have matched security and entered the proper passphrase.
When they attempt to connect, they respond with a "timeout" message. They
show high signal strength from the net.
I believe that this is a simple problem that I just cannot seem to find the
answer for. Also, while I am familiar with computers, I try to stay away from
the "Command Prompt" as much as possible due to having to work in DOS when I
was younger, so if that is where we need to solve this, please give detailed
instructions.
thank you for your assistance.