Dark materials when not using deferred rendering path

Hello, for some strange reason my in-editor and in-game materials go dark when I do not use the deferred rendering path. When i switch to any other rendering path this problem occurs. It is quite annoying as it "flickers" between the way it's mean't to look and the way it should not.

I've attached a screenshot in case you do not understand what i mean. This occurs in all of my projects, and I have tried to re-download the Unity game engine, but that made no difference. Changing shaders made no difference, this happens with all of them. You may notice in the image attached that two pieces of geometry are browner in colour. They are using the standard capsule and cube materials, but are being effected.

Thank you for reading! Any help would be greatly appreciated.