Ive noticed that when driving on the motorway if i steer the wheel gently it wont do anything, i have to keep steering till it seems like its clicking iinto place and then the car veers sharpely!! Its fine when at low speeds though?? Its also developed a rather annoying knocking noise, is this a sign the steering rack / columm is on its way out or could be something else, driveshaft maybe??

Any ideas peeps as its starting to get on my nerves

Cheers,
Dave