I've read in the owner's manual that if there a power interuption or other similar issue when operating the pano roof, it will need to be reset. Unfortunately the folks that do this (per the manual) is your friendly BMW service tech.

On a side note, mine is in the shop now for the front panel binding when it pops up in vent mode. The tech found the black receiver channel (what the back edge of the front panel sets in to go flush) was bent and snagging on the panel.

After replacing this part, the tech has to "re-intialize" the roof so it properly sequences again. Hope this helps...