peer to peer between 2 XP pro PCs

I am running XP Pro on two PCs in my home, both with Gigafast NIC, connected to a 3COM Gigafast switch. The problem I'm going to describe existed prior to upgrading the network from the standard 10/100 cards & switch. One PC (Master) has extensive drive space, and stores photos, music, and video for use on both PCs. Drives for each are mapped from the second (Family) PC. The problem started quite a while back when one PC would access the drive of the other - either through a mapped drive or network neighborhood - both PCs would freeze up requiring hard boots. I have Netbeui installed on both PCs. They can see each other, and you can browse what you have permission to, but copying or moving files across the network freezes both PCs. I suspect if this were a simple configuration error, I'd get an error message instead of freezing up. Has anyone seen this before? Any help is appreciated.