Brick wall falling apart?

The walls of my fairly old house are made of bricks and we never had any problems with them until recently. In one particular corner, all the bricks are disintegrating and we're constantly forced to sweep away brick dust. All the other brick walls, however, are fine. What could be causing this? Could this be the result of a lot of exposure to water (the rain is constantly dripping down that wall), or perhaps bugs of some sort making the bricks softer and more fragile?