When attempting to view shared files on XP systems on a Vista system, the files cannot be seen.

Usually the XP systems cannot see the Vista systems. In this case, you can usually access the files from a Run command, but cannot see them in the view network window.

Resolution:

Turn off the Guest account on  the Vista system.

Start >> Control Panel >> User Accounts >> Manage another account >> Continue at the UAC prompt >> Guest account >> Click Turn off Guest account >> OK