Which Firewall? HIPS, or ENS? The ENS Firewall rules by default have rule groups called "Windows AD Authentication" and "NetBIOS" that IIRC have all the firewall exclusions needed to access SMB/CIFS shares.
It's most likely a rule for File and Print Sharing needs enabling to allow TCP port 445 (SMB) and UDP ports 137-139 (NetBIOS)
Assuming the ENS suite then the firewall log, which is typically in:
will reveal if the firewall is blocking requests. It'll even state which rule is the culprit. Then you can adjust accordingly.