I have problem in vray animation render :S


hello everyone , i have problem in my animation render , when i start render my file in each frame i saw diffrent kind of GI that i cant fix , i try many thing like deleteing lights or object but still the same , if u take my images and see them in raw u can see there is some diffrent dirt on buildings or the objects in center of view in each frame , plz see and if u have any idea tell me about it , ty very much.

this link that u can see the sampels