If you still cannot capture an image in Full Auto Mode after following the suggestions in these topics, select the Home Mode or Professional Mode. And clear the Thumbnail Preview check box, preview, then create a marquee manually.
Drag your mouse (move your mouse while clicking the mouse button), when the cursor shape is '+', to create a marquee.
When you move the cursor over the marquee's line, the cursor shape changes to an arrow. Then you can drag the marquee to change its size.
When you move the cursor inside of the marquee, the cursor shape changes to a hand. Then you can drag the marquee to move it.