2006 bmw 525i "transmission fault, gears can be engaged without depressing the brakes. drive moderately. What can it be?

I have a 2006 bmw 525i and today the car gave the message "transmission fault, gear can be engaged without depressing the brake. Drive moderately." It wont pass the 1st gear while the message is there but after i run it about a mile or two and shut off the car then turn it back on the message is gone and when driven the gears change normally like nothing happened. What can it be?

It does not make sense because if the Radio/Cassette Unit is stock, the only way that I can see is somehow the illumination wire get the power feedback from the headlight switch or the wires rubs/chaffing/shorting somehow.. That's the only explanation if the system is stock and nobody ever touch it. No modification, nobody ever remove the stock unit. Still, it almost impossible after looking at both stereo system and headlights wiring diagrams. See the included diagram for the stereo system:.

Edit: Read this thread and it may give you some ideas. Hard to believe after more than 20 years and nobody ever touch/ remove the Radio/Cassette unit.
http://honda-tech.com/showthread.php?t=2...

Update : It seems to rock or shake then it goes. it has only happened about twice in the last couple of months but a couple days ago i turned it on and it shut off on me and when i turned it back on it started doing the shaking or rocking thing it turned back off and then it was fine. it ran fine to work then i thought i herd a clicking like noise.
my brother normally looks at it and brings it to the shop he works at and im having a hard time getting my brother to look at it. is this a serious problem?

the pump isnt like dirt cheap, you can price it online at any box store. problem is most diyers do not have a pulley tool, or the tools to do this parts swap. honestly, you clear a few things from your way, remove the belt and tensioner and idler. then remove the bolt and 2 nuts. break the pressure line loose, then remove the 2 studs the nuts came off. lift the pump and bracket away, remove both lines. installation is reverse of removal.find someone with a puller to remove the pulley or rent one.
if this is the nissan motor, its easier, the pulley isnt pressed on

my 1995 dodge stealth ac fan and compresser stopped working at the same time what could be the problem ...blower and all speeds still work and still changes to hot...?