I discovered this fun little issue today.
I right clicked on an object. The object was 1 prim, just a rectangle with a texture on one of its sides. I chose "Edit" because I wanted to look at the properties of the object. The object disappeared.
So I right clicked another object. This time there was no context menu at all, the object just vanished. I repeated this several times before deciding that I wanted to stop sending pieces of our build into oblivion.
There is no warning about returning the object. There is nothing except the instant disappearance of *anything* I right-clicked on.
I restarted the viewer and now right-click is behaving as it should, but those prims that poofed are not in my inventory and haven't returned to where they were rezzed in the sim.
What do I do now to get those objects back?