Linux error id: cannot find name for user ID xxxxx when using Domain Authentication

We recently had a problem, after re-doing some samba configurations on RHEL 5, in which a user would log in (successfully), but then be presented with the follow errors:

id: cannot find name for user ID 10001
id: cannot find name for group ID 10000
id: cannot find name for user ID 10001

Of course, none of our domain ACLs worked for this user, either, which was a real problem. Finally, after running through the more obvious problems (communication with domain controllers: verified with wbinfo; uid and gid allocation and linking: set explicitly with wbinfo; winbind cache (cleared, both in /var/cache/samba and /var/lib/samba); date/time discrepancies; domain membership), we found the culprit: file permissions.

NT_STATUS_PIPE_DISCONNECTED with Samba Winbind and Windows Server 2008 R2 Domain Controller

We recently upgraded our domain controllers to Windows Server 2008 R2, and our RHEL 5 authentication through our Windows domain immediately broke.
Here was the error:

[2010/06/21 09:32:57, 0] rpc_client/cli_pipe.c:rpc_api_pipe(790) rpc_api_pipe: Remote machine adserver.my.edu pipe \NETLOGON fnum 0x8007returned critical error. Error was NT_STATUS_PIPE_DISCONNECTED

A little searching online shows a lot of people with this or related problems, but the solutions appear to be many, and there mostly isn’t a solution posited.
But there is this: https://bugzilla.redhat.com/show_bug.cgi?id=561325
In short: there's a bug in the samba package that prevents it from working with Windows Server 2008 R2 domains. If you’re running into this problem, the solution is to remove your existing samba installation and install, instead, the samba3x packages.
Note that samba3x was a "technology preview" from RedHat, which means that it offered little support for it. This has changed, and it's now a supported package in RHEL 5.

yum erase samba samba-common
yum install samba3x samba3x-client

You’ll have to re-do your configuration, so it might be worthwhile to back up your /etc/samba/smb.conf file.