There are currently two registry settings required to be added on the Windows 7 client prior to joining a Samba Domain. These are:
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:
DWORD RequireSignOrSeal = 1
DWORD RequireStrongKey = 1