is that water in the bottom left corner?  if so - i found your "problem"  if that's water, do you have displacement on it?  if so... turn it off.  for that matter, turn off all displacement for now.

Also, if thats an infinite water plane - you dont need it.  try a cube, squished on up-down and stretched on depth & width, apply your materials, and viola - very realistic water from a cube - and cubes like displacement more than infinate planes.  just stretch it back as far as ... i would say to somewhere behind the little... pond? that i'm thinking i can see in midground (sorry, have a hard time seeing smaller images, and im not really awake yet)

another idea....in atmosphere......take GR down to GI or lower, GI down to AO or lower, take AO down to GA, and take GA down to Standard.  i'm thinking that scene is either a GI or AO, not radiosity...., so, click on the radial button that's above whichever one is ticked right now and try. 

very cool lookin so far, though...
~meli

Rarer than a hairy egg and madder than a box of frogs....

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