Plane is black

All of a sudden when I ran the game the plane for the sonic waves was black:eek: this wasn’t happening before…

here is the blend.
http://www.pasteall.org/blend/3295

i downloaded the file but it works good here http://dl.dropbox.com/u/9374255/a1.jpg (you also want to click two sided option in texture face)

ya I guess it was just a glitch it worked after I restarted my computer.