Task Scheduler failed to start - Error Value: 2147943645.

Over the weekend one of the client servers stopped running scheduled tasks with error 2147943645. 

The fix was really simple and is basically setting the task to run even when the user is not logged in:

Open the task and configure the user settings as below:

The solution was found at the following site:

http://wss.boman.biz/Lists/Posts/Post.aspx?ID=55