SelfLevel SUSP.INACT warning appears...why?

[PearlyWhiteX5]

HI,

I been noticing that when I wake up in the morning my x5 is completely dropped in the back. Most of the time is just in the right rear side and when I open up the doors to my car sometimes the car starts rising again. On rare occasions I find the whole rear of the car has dropped. I then continue to drive off and sometimes the car drives very strange like a low rider bouncing all over the place. Recently I noticed a small icon on my dash wish an SUV drawing with arrows pointing down I am speculating it has something to do with the self leveling. Sometimes when I get out of the x5 the car seems fine but then a few minutes later I hear the noise as if air is coming out from somewhere on the right rear side of my car and the car starts to drop. I really need help and don't know where to start. Does this sound like an easy fix like just a fuse or can it be a pneumatic spring (airbag). I don't want to bring it to the stealers and have them charge me all crazy monies. WHERE TO START???

ANy diagrams help would be greatly appreciated. I am pretty handy.