D-Link DIR-655 :: Setting Up File Sharing Between Computers On WLAN

When I was using my Linksys router, I had no difficulties setting up Windows File Sharing on my computers but since I upgraded to the DIR-655, file sharing have hardly worked.  Sometimes I could get one of the computers access files on another, but not the other away around.  Most of the time, none of the computers have access to the files on any of the other computers.  Two of the computers run Windows XP and another one runs Windows Vista.  All computers are on the same workgroup and able to connect to the internet through the router.  When calling D-Link tech support, I am told that they dont support file sharing and that I had to contact each computer's manufacture's tech support on the instructions on setting up the file sharing (each computer is from a different manufacture).  One of the tech supports did drop the slight hint that I needed to recreate the home network, but when I tried to do that, all I could find is the settings to connect to the router (which I had set up when I installed the new router) and to enable file sharing (which is already done) and to assign the workgroup, which they were all are already assigned to the same group.