A number of complaints from Digital Rebel EOS owners reported that the auto focus feature suddenly stopped working. In some case the picture was showing a dark shadow on the lower side.
The problem is a factory defect caused by a factory defective autofocus sub mirror. The problem is known to most repairers ( and sadly to users ). Although the defect due to design problem, Canon never acknowledge that this is a factory defect, and never issued a recall and free repair notice for Digital Rebel defective autofocus.
THe repair is done replacing the mirror. The cost ranges between $120 and $180.
As first line of action, check any of the links below, and call Canon. Complain, and see if you can get discounted repair.
If that does not work, the alternatives are using the camera with no AF, or having the camera repaired at own expenses. Often the sub mirror may get even more stuck, and pictures start showing the black shadow from mirror on lower part of the picture.
This is the cause of your troubles:Here one of several repair websites dealing with the problem.
"Most autofocus repairs are related to problems with the small mirror under the main mirror (known as the sub-mirror). There is a plastic post that operated this mirror which sometimes breaks. We replace this post with a brass pin so that the problem will not recur. "Here one of the many forums on the problem. Please read the testimonial from other users, it is quite instructive.Other forum.Here replacement pin.Here how to do the repair.
Here Canon contact:Canon technical support phone number.