There are currently two registry settings required to be added on the Windows 7 client prior to joining a Samba Domain. These are:

    HKLMSystemCCSServicesLanmanWorkstationParameters
        DWORD  DomainCompatibilityMode = 1
        DWORD  DNSNameResolutionRequired = 0

Samba also ships with a registry patchfile that users can apply directly. The patchfile can be found in recent Samba sourcecode: $SOURCE/docs-xml/registry/Win7_Samba3DomainMember.reg or in Samba Bugzilla here: https://bugzilla.samba.org/attachment.cgi?id=4988&action=view

Make sure to either reboot Windows 7 or restart the LanmanWorkstation service after setting these entries.

Do not edit any other registry parameters (NETLOGON) that have been seen in the wild. If you have already modified your Windows 7 registry, please make sure to reset the keys to their default values.

If you have changed the NETLOGON Parameters, make sure and turn them back to '1' as shown below:

   HKLMSystemCCSServicesNetlogonParameters
       DWORD  RequireSignOrSeal = 1
       DWORD  RequireStrongKey = 1