What's wrong with this plant.  Anyone have any idea?

This plant, which I believe is a type of ficus, was beautiful 3 weeks ago.  Then all of a sudden, the leaves are dropping to the floor and many that are still on the plant are turning brown.

When I purchased the plant, the clerk told me this plant was practically indestructible.  Well look at it now.  I have lots of plants around the house that do quite well actually, but I'm not having much luck with this one.

What do you thinks going on with it?