Locked door
I've seen a few. None on an ILS though, all on non precision approaches where Boeing, in its endless wisdom, decided that IANs FMC computed GP gives the same warnings as a "real" ILS, not only the same indications. Which, with just half a hP off the real QNH can very easily lead to GPWS warnings on short final.
Wrote an ASR on the first one and got a response back: yes, it is a known issue and can happen easily, simply continue visually and land in the touch down zone.