One problem related to power steering pump has been reported for the 2000 BMW 540. The most recently reported issues are listed below.
Lucky I was stopped when this occurred. My engined made a terrible noise and cut out. I went to restart my engine and noticed that all my indicator lights were on. I went to drive and my power steering was completely shot. Come to find out that my power steering pump broke with no real warning. If I had been at a high speed this could have lead to a serious injury.