2003 Renault Laguna Suspension collapsed on front passenger

I have a 2.0l 2003 Renault Laguna, I've only just bought it and I am the second owner.
When I started to move away from the kerb, there was a slight bang, and then the steering felt strange and there was a rubbing noise. I stopped immediately, so I had moved maybe 6feet forwards. I then got out of the car and looked round. I found the front passenger side of the car has dropped so that the wheel is almost rubbing on the body of the car, and must be rubbing when the steering is turned.
What could have happened, and what might have caused this? Before I parked I had completed a 300mile round trip on good roads without any noise or problems, and the car has been well serviced.