Jenna works for your company's Human Resources department. For several years she has volunteered to instruct new and present employees on the use of office applications in a special training lab environment. Due to the sensitive nature of this environment, security policies are more strict for the lab than the rest of the network. A more refined policy was just set in place by your administrator last Friday. On Monday, Jenna calls you and explains that she can no longer log into the lab machines locally. After further troubleshooting, you discover that any user that is a member of the "Lab Instructors" group can no longer log into any of the lab machines. What is most likely the problem?

Based on the scenario being described within the question it can be said that the most likely problem would be that the "Lab Instructors" group has been removed from the "Allow log on locally" policy. This policy specifies the individuals or groups that are allowed access to the local computer network. Being removed from this policy would prevent access, just as is happening in this situation.