I manage a SBS 2003 network that supports approx 25 workstations - all XP pro. Recently, they added a new computer - Windows 7 pro. The issue appears to lie in DNS. Here are the issues:
-can ping the DC by name
-can ping the DC's IP address
-cannot browse file shares - "cannot find server' by either IP -or- name
-cannot join computer to domain - "cannot find domain controller" error
-can browse Internet with no problems
-nslookup usually fails, but sometimes reports correctly
-this is a brand new Dell Latitude, no AV yet, nothing else configured
SBS 2003 controls DNS, DHCP, Exchange, file sharing, etc.
My personal laptop with Windows 7 pro has the same issues, as well as another Vista laptop I tried. All XP workstations have no problems.