Is this a bug

I run at a brand new iMac Intel 10.6.7 21.5 inch 64 bits and Blender 2.57 64 bits and made a wall (plane) with a hole look like a apple.
I made a apple with a circle and extrude to same size as the wall. But this dont work.

To show the problem I have exaggerated the size. At top View you see a tick apple

If you look at the side view the apple is very thinn. Same apple ??

Look at my blendfile and let me know. This have never happen before
Thanks in advance

Not a bug.
You must have accidentally checked ‘xray’ under the object tab (under ‘display’ panel) of the big plane.
Uncheck it and you will see everything is right

Greg thanks for helping .

You solved my problem. I uncheck the x-ray button.