Yudi:

I had a look at your model and noticed a few things.

1 - When rendering "fast" there was no problem, only when using "best".
2 - The "Schneider" sign doesn't render correctly on my computer (Ubuntu with SH3D 2.5): The sign is black and the lettering is black as well. The letters are visible because they have a speckled edge. This suggests to me that you used a GIF as texture and that there is a (slight?) problem with the transparency.
3 - When making all walls and all furniture white, your model rendered without a problem using the "best" setting.

There have been some reports that there is a problem using large size textures. I also read that it is preferable to have textures with sizes that are a multiple of 2, e.g. 512x512 or 128x256 pixels.

You may try to change some of your textures and see if this solves your problem.

Hans