Thanks for the comments people ^^ I dont think that I would be allowed to show wireframes, but its nothing special anyway, my wireframes are really messy :D
If you enable the wireframe, does it still happen? If it shows fine with wireframe, I have the same bug, but usually just using a mental ray shader fixes it.
the way i do wireframe renders is clone the object, add a push modifier with a push value of .3 or less, then apply a standard material with the wireframe box checked
The script I was referring to allows you to render your model with a wireframe attached instead of having to do a bunch of little tricks to get the wireframe to show in the render.