I had that happen to me. I had to drop someone off at the airport. I was gone for maybe 30-40 minutes and when I got back in the steering wheel and neither front seat would adjust, and the rear window sunscreen would not operate. We stopped at a restaurant on the way home and were out of the car about 30 minutes. Got back in, same thing. First thing I thought was a fuse, too, but three of them would have had to go bad at the same time to affect all of these things.
The next morning everything worked fine. Apparently, the car "healed itself" overnight! LOL A couple of weeks later I took it into the dealer for an iDrive issue and mentioned the problem. They could not duplicate it nor did they find any error messages that had been thrown off. It has worked fine since then (6-8 weeks).
'05 545i with Sport/Cold/Nav/Sat