Shadow problem in Unity 4.2

can someone help me with this.please
The Mesh casts shadows to itself and it looks ugly.
but when i use DX11 it works fine however it crashes when working on a huge files.

This isn’t an expected unity behavior. I think you have something wrong in your setup. Without supplying a zipped project, you won’t be able to find help. I don’t know if you can attach zip files here.

If you’ll try to attach it, don’t forget to enable meta files in editor settings and zip only the assets and projectsettings folders, nothing more.