Problem with Depth of Field effect

I have tried the Depth of Field effect( from shader replacement example) in my project (with the same configuration and components like the example) but in my project, (I have a big terrain and some models) I get a white screen with graphic artifacts and not any error in the console. Of course I have Unity Pro!
(I forgot to say that the original DOF example from shader replacement works fine)

What is your graphic card and OS information?

Are you using any other effects in your project? Particularly, are you using the water shader? Try turning any post processing effects but field of vision off, and report back.

My graphic card is a Nvidia 8600GT and the OS is Leopard (5.5) but I think it is not so important because the effect works well in the DOF sample ( the scene with the cubes and spheres ).
Yes, I am using the water shader but the problem is the same without the water shader and any other image effect…

Hey,

could be that it is the quality settings u are using.
i mentioned that when i played around with DOF. there must be something
maybe antialiasing or something else
try to set down to good or beautiful.