If you are running scheduled tasks for data summarization and the scheduled tasks fail, check for the following condition.
The Windows Event Log service fails to start. This is due to the presence of an empty Parameters subkey.
The Windows Event Log service is a dependency for the scheduled tasks, so scheduled tasks stop running.
Delete the empty Parameters subkey under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\eventlog and restart the Windows Event Log service and schedule service. (Do not accidentally delete the eventlog regkey itself!)