The Network Load Balancing (NLB) driver on the host tracks connections to maintain client/network affinity configured on the NLB cluster. If the driver is not functioning properly, NLB may not be able to track TCP connections or may experience load distribution errors.
Disable and enable NLB network adapters
If Network Load Balancing (NLB) is unable to open a TCP connection callback object, then NLB cannot track TCP connections. Although NLB will still accept new connections, it will not track the connection state, which may cause the affinity that is maintained by the driver during the connection to break. You should disable and re-enable the network adapter before attempting to bind NLB to the adapter again.
To disable and re-enable all network adapters:
Click Start, click Network, and then click Network and Sharing Center
Under Tasks, click Manage network connections.
Right-click the network adapter you want to disable, and click Disable. If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
Right-click the network adapter you want to enable, and click Enable. If you are prompted for an administrator password or confirmation, type the password or provide confirmation.