Just more info... in ProSeries Professional people can customize their views.  This year we added the ability to drag columns away in order to remove them one by one (in addition to dragging them to reorder).  This feature is actually in Basic too ... somehow it looks like all the columns got dragged away for EF Client (but that takes a lot of work.. so I believe there must be some sort of bug with the ctrl zooming or something such that you accidentally got in this state).

If it happens again, I think you can just go to HomeBase -> Reset Current View and that will basically do the same thing as swapping the files.