Internet Connection Sharing but no wireless network

I have file and printer sharing enabled on all three of my computers. The Dimension 2350 is connected to the router with an ethernet cable and can access the Inspiron 5150 and the Dimension 2400. The Inspiron and Dimension 2400, however, can only access each other, and not the Dimension 2350. If anyone has a solution, I would really appreciate it. FYI: I can connect to the Internet from all three computers.