PRND321... Well, on my last car it was.
Anyways, you know those lights that go on in the back when you have the car in reverse? Well, as you slide the gear selector from whatever gear you're in you pass through "R" or the Reverse gear. When passing through it, the backup lights go on. So the problem is probably a ground issue like tein said, and it has to do with the backup lights.
If its not that, perhaps its an electrical issue with the transmission, which I've heard can be an absolute pain.
You probably have a open wire which keeps on grounding out in something metel find that wire and follow or possibly that wire might be loose to it's something really simple
Wow both of you sound really right on, so thanxx a lot :]
No problem ;)