render and mesh modeling bug

Look at the corners of edited plane… render it or just preview in 3d view… what is this?!! … the corners are stretched randomly… any way to fix this? the bug is appearing in BGE, Render or just 3d view…

here is the blend: http://dl.dropbox.com/u/1835557/render-bug.blend

Please explain what you are trying to do or expect to see. What’s stretched randomly?

i mean this:

http://dl.dropbox.com/u/1835557/renderbug1.jpg
http://dl.dropbox.com/u/1835557/renderbug2.jpg

the corners are different… and i want to know why…

This is not a bug, you have non-planar quads in your mesh.
Just clean up your geometry.