Grids on floor in renderings - Mental Ray rendering question

[junxianpoon]

Does anybody run into this kind of problem?

There are grids reflections on the floor and I don't know where do they come from.
Here's is the image.

And does anybody know how to fix it?

[Brock_Lafond]

Are you using the glare lens shader?

I've experienced this a few times when using that shader.

[CAMedeck]

It's the Interpolation in the reflections of your floor material.  You can try playing around with those settings, but I've never been able to get it to work well on a very glossy surface.  You're probably best off removing the interpolation and just bumping up the samples to get a nice reflection on the floor.