After I changed IP address of my W2k server, all Trust with other domain based on NT 4 drver were broken. When I tried to establish trust again "[domain] cannot be contacted" error appear.
When I check if W2k server can resolve DC i saw following error:
C:\>nltest /dclist:[nt4 domain name]
Domain '[nt4 domain name]' is not an NT 5 domain. (Using NetServerEnum).
I_NetGetDCList failed: Status = 6118 0x17e6 ERROR_NO_BROWSER_SERVERS_FOUND