Power Steering

[Blue Thunder]

I am having a small problem with the power steering on my IS200. The fault currently is too intermittent at the moment to bring to the attention of my Dealer but I wonder if anyone else has had a similar problem and found out what it was.

If I leave the car for a few hours with the front wheels anything but straight, when I restart teh car,after a few seconds there is a loud thump with a "vibration" transmitted through the steering coloum as the power steering pump "kicks in" This doesnt happen every time.

Alternatively when I start the car if I have to turn the wheels in teh first few seconds that the engine has been running the front wheels turn as if the tyres are on ice, ie there is no resistance. This has also happened twice when I was driving very slowly and turned on full lock into a parking space.When the car is running there is no problem. The steering fluid is fine and I can find no obvious leaks. I realise the car has speed sensative power steering but this doesnt seem right to me. Any thoughts???