Importing Objects Corrupts Graphics

I have this problem whenever I start or open a new project the graphics appear fine but as soon as I import anything it corrupts the graphics, like below.

I didnt even save the project, and this corruption is still a permanent part of this project, every mesh appears like this subsequently. All I did was import an object into the project view, not even into the scene, straight away the graphics just went.

Unity is basically useless to me. I wanted to use it to preview objects for texturing and cannot do so at all. Is this a new feature or something?

click on the importer settings and select calculate normals instead of import
see if that helps

That worked thanks Maart.

Does Unity not work with smoothing groups then?, because that may make it a bit awkward to use.