Land Rover Repair: IMMOBILISER, turning the key, occassion

Question
I have a 98 Disco, after unlocking the car with the immobiliser, on occassion it won't unlock the key barrel on the ignition. Leaving the key unable to turn in the barrel. I then need toi lock and unlock the car a number of times to release the key ignition. Is it a ignition barrel problem or is the immobiliser faulty. then once unlocked it may not happen for a month.
As this has left me stranded unable to start the ignition, is there a way of by passing the immobiliser. thanks for any assistance in this matter. Mik

Answer
The problem of turning the key in the ignition is entirely within the ignition.  It has nothing to do with locking and unlocking of the doors.  Your observation in that regard is mere coincidence.

Buy a new ignition switch and install it before you're stranded.  It's a common enough problem.