The car is back from the dealer now and I am happy to report that it seems to have been cured. No warning lights and all functioning ok. Even after a long and fast drive on rough and rugged polar winter roads yesterday, still no warning lights
At the dealer they checked the log without being able to draw any conclusions, luckily they didn't do any blind attempts on changing any sensors. They cleaned some main connectors, and they suspected that one close to the gearbox could be the reason for my trouble because it was a bit greasy. Finally they reset the computer and, voilá. So far.....
Told me they had used five hours, but would charge me only for three
If I'm really lucky BMW Norway will refund me as a part of my guarantee.