We have just bought a 2002 Discovery and the feeling through the steering wheel is very lacking. It feels very light almost to the point of having a mind if it's own. The ACE system lights up a red symbol on the dash after the first corner of a journey is taken. Could this be the problem?

Also there tends to be a whine from the engine when the car comes to a stop or sometimes when manoeuvring. I've checked the power steering fluid and it's all topped up.