Random glitched patches while rendering

this happened to most of my recent renders there are ceartain areas with the same properties of the sorrounding areas in a much lighter shade.

Hi! Maybe you can change some texture settings,and I will send you a screen shot. Or there maybe some reflection model in your scenes such like the window or the mirror, try to move it.
If you still have this problem, could you please send me more screen shot? And contact me at any time!