Using the Services.msc snap-in, you notice the the Task Scheduler service is NOT running, even though the Startup type is set to Automatic. When you try to start the Task Scheduler service, you receive:
Could not start the Task Scheduler service on Local Computer.
Error 1717: The interface is unknown.
This behavior is symptomatic of having the Event Log service set to Disabled.
To workaround this problem:
1. Open a CMD.EXE window.
2. Type the following commands, pressing Enter after each line:
cd /d %SystemRoot%\system32 sc config Eventlog start= auto net start Eventlog sc config Schedule start= auto net start Schedule