I don't know anything about the Task Scheduler, but you may be running into memory problems. SolidWorks is not particularly good at releasing memory, so as you open and close drawings, you may be growing your memory usage to a point where the system has problems. One workaround would be to use smaller batches of drawings.
One way to see if this might be part of the problem would be to use Task Scheduler to open a large drawing at the very beginning of the batch.
Thanks, I will try as you suggested.