Yes on the layout screen when you've selected a model it should be yellow and if it's not then you may need a new graphics card as Gil mentioned. I might add also, check the brightness levels on your monitor.
Something makes me think that the value curves that you have set for brightness may be turned down. That would affect what you see in the model & house screen during playback . On the layout screen does the model have Gamma set at to 1.0 & brightness to 0?
Something else you can try is in appearance settings, increase pixel size and pixels are not transparent.