Yes, ive had alot of problems, sometimes yes, sometimes no. Basicly when i add a ship (I use to be careless, now it takes alot of work, im not sure why) I copy/paste an orginal, rename it, make sure it shows up, then edit it one section at a time.
Every once and a while, a ship will stop loading With No Invalid ship.txt entry. I can find no rythym or reason to this. Course this all started after i added fighters to the game.. but then agian, it did it too without em (maybe i just noticed more heh)