I have just started using Unity and have found when I create a game object (i.e., a cube) it appears in the heirarchy, and appears to be able to be modified using the toolbar, but the game object never actually becomes visible (i.e. you can find the object in the scene but nothing actually appears or is visible in scene or game mode). If I however load an already existing scene I can see and modify these game objects no problems, I just can't create any new game objects.
I have taken a screenshot to illustrate the problem http://s1086.photobucket.com/albums/j460/fha221/?action=view¤t=unity.png
Are there any settings which may be preventing me from seeing game objects? I have tried switching between RGB, Alpha etc and Scene and Game views as well as uninstalled and reinstalled Unity.