sounds wierd.
Sometimes i get something simalar to that when import a obj model. It just doesnt show up.
But what i would do, is open your outliner, and check to see if the geometry is listed there. Eg.. cube1
If it is, it means its there but probably just lost its material shading.
So click on the object in the outliner, then right click on the screen, and try to re-add the material to it.
Thats all i can think of right now.