Just thought I'd post this-it is common on B M W s many models including some of the 5 series from the late 90's on: my interior dome lights cycled on and off, the radio started shutting off automatically while driving, various warning lights came on but eh passenger airbag warning came on and stayed on. One of the better ways to test for ignition problems is to pull down the passenger visor and open the mirror/vanity light. The light may or may not go on but it will briefly turn the headlights off and on at night.
The problem is the ignition switch (not the key cylinder but further in) you can find them on ebay for around $50 or $90 at bavarian auto. its pretty easy to swap out the old one and put the new one in...just need a properly sized torx driver. All the problems were solved and have not come back weeks since the new switch has been put in ( 20 minutes to swap it out tops)

Thanks SherpaB, it solved the same issue my 2010 X3 e83 was facing.