When I open a photo in Photoshop Elements or Photoshop and zoom in on it so much that some or all of the image goes off the screen, I can't crop the image anywhere near the corners without the image rapidly moving once I drag the crop mark. How do I "freeze" the image so it doesn't start scrolling around, so I can then start my crop from any of the corners of image?

I've found that by using the select tool and then going to edit-cut works best for me. The selection tools offers more control and there are three different ways to select the area in the image you want to crop; square, circle, and free-form (or poly).