Message : please wait for the system Event Notification service - 2008 R2 Server

Log Name:      Application
Source:        Microsoft-Windows-Winlogon
Date:          9/25/2014 9:48:05 PM
Event ID:      6005
Task Category: None
Level:         Warning
Keywords:      Classic
User:          N/A
Computer:      Server.INTERNAL
Description:
The winlogon notification subscriber <Sens> is taking long time to handle the notification event (Logoff)

Log Name:      Application
Source:        Microsoft-Windows-EventSystem
Date:          8/22/2014 11:32:47 AM
Event ID:      4627
Task Category: Firing Agent
Level:         Warning
Keywords:      Classic
User:          N/A
Computer:      Server.INTERNAL
Description:
The COM+ Event System timed out attempting to fire the Logon method on event class (D5978650-5B9F-11D1-8DD2-00AA004ABD5E) for publisher  and subscriber .  The subscriber failed to respond within 180 seconds. The display name of the subscription is "User Monitor Subscription". The HRESULT was 800705b4.

Receiving the above errors on Application logs, and when running : sc queryex sens

SERVICE_NAME: sens
        TYPE               : 20  WIN32_SHARE_PROCESS
        STATE              : 4  RUNNING
                                (STOPPABLE, NOT_PAUSABLE, IGNORES_SHUTDOWN)
        WIN32_EXIT_CODE    : 0  (0x0)
        SERVICE_EXIT_CODE  : 0  (0x0)
        CHECKPOINT         : 0x0
        WAIT_HINT          : 0x0
        PID                : 972
        FLAGS              :

Had to kill the PID , winlogon.exe for the logged in user or reboot the Server to resolve this.

Not sure if this is applicable : http://support2.microsoft.com/kb/2383928 as mine is a DC and not a Terminal Server.

Arun