Canonrumors is reporting on a problem with the Canon EF 40mm f2.8
If pressure is applied to the lens barrel while the lens is mounted to the camera (pressure can be applied even while attaching the lens cap or while carrying the camera with the lens attached in a bag), the autofocusing function of the lens may stop working.
It seems they will have a firmware update for the camera in August to fix the problem, but for now just remove the lens and put it back on.