We were having issues with a few macs in the office, whereby they could connect to Windows 2003 NTFS shares and read the data but upon trying to write to shares it would fail with no error message whatsoever.

The folllowing fixed this with the following performed on the DC

Start -> Administrative Tools -> Domain Controller Policy

Security Settings -> Local Policies -> Security Options -> "Microsoft network server: Digitally sign communications (always)". It should show "Enabled" by default. Double-click on it and set to "Disabled".