Big, big, pixel black.... everywhere , everywhere , why, I'm this ?

[bla bla 2]

Everything is in the title.... 

[archonforest]

Any error message?
I had something similar before but TG restart handled it.

[Kadri]

Not sure if you use reflection but i had a problem like this with reflections.
Try rendering without reflection and see if it is related to that.

[Oshyan]

You have Antialiasing Bloom enabled and are using an Pixel Filter that doesn't work well with it. Use a different filter or disable Bloom.

- Oshyan

[N-drju]

I had this problem with downloaded object. The texture it used caused the problem. Check if it is some texture's fault.

Also I've seen another topic on this where it was said that the texture was in some way "incompatible", so you might need to use some other color here (retexture).

I wanted to give you some answers in French but I'm just too tired at the moment.