One of the benefits of using a virtualization product that allows you to create snapshots, is the ability to create a "point in time" to which you can always revert your virtual machines. By reverting to this snapshot, you get your VM to the state in which it was saved, and are able to perform various tasks such as testing software, doing QA, creating labs and so on.

However, one of the nasty issues of working with snapshots is when you have one or more virtual machines that are members of an Active Directory domain. When you create snapshots of such machines and restore them, you might occasionally find that all authentication involving the VM seem to fail, and face an issue of not being able to log on to the virtual machines, or not being able to access files and shares across the network. You might even get errors like this one:

Windows cannot connect to the domain, either because the domain controller is down or otherwise unavailable, or because your computer account was not found. Please try again later. If this message continues to appear, contact your system administrator for assistance.

If you log on locally (not using a  domain account) to the computer (in this example it's a Windows XP Pro client), you'll see the following events in the Event Viewer.

NETLOGON 3210

This computer could not authenticate with \\WIN2003-SRV1.petrilabs.local, a Windows domain controller for domain PETRILABS, and therefore this computer might deny logon requests. This inability to authenticate might be caused by another computer on the same network using the same name or the password for this computer account is not recognized. If this message appears again, contact your system administrator.

LSASRV 40961

The Security System could not establish a secured connection with the server cifs/WIN2003-SRV1.petrilabs.local.  No authentication protocol was available.

--> The rest is on PETRI's website :

http://www.petri.co.il/working-with-domain-member-virtual-machines-and-snapshots.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+Petri+%28Petri+IT+Knowledgebase%29