Why are my materials not renering well?
Some objects are being rendered with the material of others, without no reason. In the yaf GUI all the settings are OK.
…ya…, I can see your Desktop and .blend settings from here. 
Here is it!
http://rapidshare.com/files/414698521/Bran_room1.blend
The worst thing is that the rendering canges every time I close and re-open the file
ok, so now if you could tell us which objects and which materials you are having trouble with, and what the render should be doing that it does not…?
…and in what way does the render change every time…?
Is it the picture frames?
There is Gloss Violet which is white, and assigned to the front of the frame, and there is Gloss Violet1 which is grey, and assigned to the side and rear of the picture frame.
Bran_room2.blend (646 KB)
(Sorry for all the sarcasm, I hope you are not easily offended 
It does help greatly if you can supply as much detailed information as possible to help diagnose the problem)
There is no problem with irony. I only taught this kind of issue was already “scheduled” and “known” by the experts, so strange it is.
For example, the pavement should be rough parque. And the lowest part of the wall, you see there’s a mesh there, following the perimetre of the room: that too should be of another material, wood. You can check by pressing
“Always show current object material” or something similar, or even in the blender material system
ok I see it now. It looks like the materials may have been corrupted. I can’t say what caused it, but replacing them seems to fix it. Try this file, I have packed in a wood texture and made a new material for the floor. The plane under the floor also has the new material. It seems to render successfully
Bran_room2.blend (846 KB)
I didn’t notice the textures weren’t rendering as you forgot to pack the textures. File -> External Data -> Pack into .blend file allows you to pack the images into the .blend. You have to unpack them before Yafaray will render them.