Unity 5 freezes while building?

Unity 5 is freezing whilst building my project. Whilst building, the build progress bar gets to 'building assets for scene 0' and then immediately freezes and becomes completely unresponsive, requiring me to exit unity 5 from the task manager. I have very few assets and I have had no problems whatsoever in the editor or game mode. I also have no errors in the console and there are no problems with any assets. It does not matter which platform I wish to build to and am definitely building it correctly. What could be causing this and how can it be fixed?

There's not many other details I can give unfortunately since I am quite new to Unity, if there's anything you may need to know to help me with this problem please ask.

UPDATE

I have reimported all assets, there are no assets other than the default assets in my project and yet it still freezes.

here is a picture of the freeze.