I have found that some ships are like ghosts and can't be shot or flown into. Some of the ships I have came across are the RH Cruiser, Large train, RH BS (i was told not seen) they are the ones I can think of right now.
I've been mildly miffed by one-shot weapons since their implementation, oh so long ago. I remember the days when fights were a matter of who could aim better, rather than who could aim a single shot. - Virus