en el evento move del Formulario
puse este codigo y me funcionno muy bien
espero te sirva la Info..
Cita: if (this.Location.X <= 1)
this.Location = new Point(0, this.Location.Y);
if (this.Location.Y <= 1)
this.Location = new Point(this.Location.X, 0);
if (this.Location.X >= 1)
this.Location = new Point(this.Location.X, 0);