imobilisor or what

Hi when I try to turn my key in the ignition is some times wont turn in my 300tdi. Is it the imobilisor? If I get out lock it and unlock it again it seems to be fine its just got worse over the last couple of months. Can some one suggest what the problem is please I am a bit worried the wife may get stuck some where she dont want to.

no its more likely to be a worn key mine does it to

So does mine, now and again.
I just remove, turn over, insert and try again it always works. one day I swap it for my unused spare key.