Land Rover Repair: Discovery II air suspension problem, passanger side, discernible difference

Question
I have a Discovery II 2001 with 100k miles, this morning the passanger front corner of my disco was down, later when I started the motor I press the botom to lift the suspension up and worked fine, but when I park the car few minutes later happen again that down the passanger side, what could be the problem?

Answer
It sounds to me like the rear air springs have gone either gone down or raised up.  If the back has lifted up, it would need a new valve body.  If the back has gone down, you need one or two air springs.  I would recommend a spring conversion.  There will be no discernible difference in the ride and it is cheaper to maintain.