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