this is a big big problem on the MINI's. It was one of many problems I had with mine. I sold my MINI after 9 months and got the 135.
Check out this thread:
http://northamericanmotoring.com/for...ow-dipper.html
Try the reset option.
Hold button down for 15 seconds, then hold button up for 15 seconds. It resets the window to know where the stop points are.
It only worked on my MINI a few times. They ended up re-doing the software.