have to reboot to see network

Hi, I hope someone can help,

I have a network at home consisting of 2 Win2k Pro
Computers, The Main Family PC which hosts the internet
connection (via wingate) and My own pc. If I switch my PC
on after the main family pc the network doesn't seem to
work, I can't ping the other pc or access it's network
shares, if I then reboot the family machine and my machine
the network works, until i shut down my machine. THen the
network stops working again until i reboot both machines
again.

It's driving me nuts, anyone have any suggestions

TIA