I have tried every which way, but can not get PS 12 to crop under the expert option. I use the tool to mark what I want, but it make a rounded edge rectangle which would be tolerable under some circumstances. However, it will not crop. I can copy and paste, but again doesn't work.
It looks like you are using the rectangular marquee tool (shortcut M) instead of the crop tool (shortcut C).
The rectangular marquee tool has an option to 'round' the corners.
If you use the rectangular marquee tool without corner rounding, you can use the menu Image/Crop to crop your image.