Woah,
Thats crazy… I wonder whats going on
Have you got any terrain, grid plane or anything else in a normal position ?
Maybe check Disable Editor Cell Snap
Manually type in 0 in the Z Location box
Maybe drop in a grid plane, manually scale it to something like 16,16, 1 and location 0,0,0, see if you can place objects on it ???
I cant put the location 0 0 0 in that mechine