To answer my question, yes I have the same immobiliser problem as many others.
And after a bit of testing I discovered one more thing, if you watch the little red light in the instrument, you can tell beforehand, if the b.... thing will start or not!
When the car is parked, the red light will flash every one sec. (you should now know which light I'm talking about.)
When the key is inserted and turned, (ignition on) the red light will either light constant, or flash every half sec. if it lights constant, you can start the car, if it flash every half sec. just forget starting the car.
Now just remains to find out exactely why the main key somtimes fails to turn off the immobiliser.
Steve, you open the key by sliding the two halfs apart, one side of the key has an arrow showing which way to slide.