This is because ports can become error disabled when they detect certain errors or violations on the network, such as a loop, a security breach, or a duplex mismatch. When a port is error disabled, it shuts down and stops forwarding traffic until it is manually re-enabled by the administrator. The users who were moved to different desks may have plugged their devices into ports that were configured with different settings or security policies than their original ports, and this may have triggered the error disable state. The source of this answer is the Cisco ENCOR v1.1 course, module 3, lesson 3.3: Implementing EtherChannel.