The System Event Notification Service (SENS) monitors and tracks computer events such as logon, network, and power events in the Windows operating system. It also notifies the COM+ Event System service subscribers for these events.

If the System Event Notification service stops, subscribers to the COM+ Event System service do not receive event notifications and the following problems occur:

• The following Win32 APIs do not work: IsNetworkAlive and IsDestinationReachable. These APIs are typically used by mobile applications on portable computers.
• ISENS* interfaces do not work, and SENS logon and logoff notifications fail.
• SyncMgr (Mobsync.exe) does not work properly due to its dependency on network connectivity information and logon notifications from SENS.
• The COM+ Event System fails when it tries to notify SENS of events.
• The Volume Shadow Copy Service does not load properly, which causes the Windows Server Backup API to fail.

This service is installed by default in Windows 7 and Windows Server 2008 R2, and its startup type is Automatic. .

When the System Event Notification Service is started in its default configuration, it logs on by using the Local System account.

The System Event Notification service is dependent upon the following system components:

• COM+ Event System
• Remote Procedure Call (RPC)
• DCOM Server Process Launcher
• RPC Endpoint Mapper

The following system component is dependent upon the System Event Notification Service:

• COM+ System Application