I have been trying to connect 2 computers (XP and 7) via a 'twisted cable' and the following may be of interest as, initially the 7 computer could not see XP although the XP one could always see the 7 one. I assigned unique IP addresses to each, default gateway, subnet mask, etc, and clicking the Windows 7 network icon showed nothing, as usual. I then remembered an old trick from the Windows 2000 days and the following works:
Select 'Map Network Drive' and enter something like '\\XPCOMPUTER\SharedFolder' and click finish (Do not use Browse as it will not find anything). The shared folder shows up immediately, although nothing appears when clicking the Network icon. This network can then be assigned as 'Home Network'. Why is this happening?