home networking with router on xp pro one pc cant access the other

[starman47 0]

I have a router set up feeding both pc's with internet conection computer A ,, cant view anything on computer B even though i have set both pc's to share with each other ,, when i go to my network places in windows explorer on computer A , i see Compter B ,,, but when i click on to view the contents i get a message saying i dont have permission to ,,,

but when i'm on computer B i can access the shared things on computer A ,,, without a problem ,,, i cant find a way to open anything that allows me to give permissions ,,, please help me !!!!!