This issue seems likely to be a problem with the installation of a Active Directory (AD) integration product for authentication called LikeWise. This product is no longer available, to my knowledge.
You can read more about it her in this articled titled: How to join Linux server into Active Directory on SBS 2008 network. It's also listed here in the Wikipedia page on products that support SMB as well as here on the Active Directory Wikipedia page.
Here are two methods for identifying this product's been setup.
1. Lsass error messages
20111006152006:ERROR:Lsass Error [ERROR_BAD_NET_NAME]
Network name not found.. Failure to lookup a domain name ending in “.local” may be the result of configuring the local system’s hostname resolution (or equivalent) to use Multi-cast DN
2. Modified nsswitch.conf
And these modifications to your
passwd: compat winbind lsass
group: compat winbind lsass
You should be able to safely leave it installed and change your Name Service Switch configuration file (
nsswitch.conf) so that it uses just your local files for authentication.
I also dug up this Launchpad bug that covers uninstalling LikeWise-open. There are some things that it doesn't do to revert your system when you uninstall it. They're covered in this bug along with how to manually undo the install.