How can I fix Range Rover wheel shake?

Can anybody help me out there. I have a P38 2001 Range Rover. I've got bad shake on steering wheel which occurs when dirven approximately 1/4 mile from cold. It shakes steering wheel badly for about 30 seconds to a minute and then stops completely. Doesn't happen again till started again next day. I have checked props, renewed brake discs and brake pads, checked wheel balance etc. but still shaking in wheel badly. Please help?