Low resolution lines, "dark" overcast and missing material texture

Hi, does anyone know as to why my model has began displaying low resolution lines in plan view and also all my components have lost their assigned display colour in shaded view (perspective) and as you can see, when i try and take it over to rendered mode the model is barely visible, with assigned materials not revealing the material texture, for example instead of a black slate roof i am seeing block dark grey.
Thank you

Hi Alessia -
Please run the Rhino SystemInfo command and copy-paste the result here.