net use <drive letter> \\machine\share /USER:username still prompted me for a password.

nslookup hostname worked fine.

I'm not sure it matters but we are using NIS here. On the samba machine I can ypcat passwd, group fine. When I ypcat server I get two entries, both the same IP and name.

ypcat hosts |grep machine1
XXX.XX.XXX.22 machine1 machine1.domain.com
XXX.XX.XXX.22 machine1 machine1.domain.com

Also, wbinfo -g/u works as it should.