vista-XP network

I own a compaq presario 920ea (windows XP), an bought last week a HP pavilion
6535ea (windows vista) to replace it. Unfortunatly I can't conect the
computers trough a network. I tried a crosslink cable, a hub and 2 diferent
routers. I have disabled both firewals (Zonealarm and norton internet
security respectively) and tried a lot. I can see the drives, directories,
files and even the miniatures of the fotos in both computers (they are
shared), but i can't copy files beteen computers. They start copiyng and them
I get the mesage "Lost access to the location...".
I Can't figure where the problem lies, i'm considering returning the
computer to the store (I've already lost two weeks to this problem).