First of all, let me congratulate you on an absolutely incredible project! I adored Privateer, and this ASCII realization adds an extra dimension to it somehow... maybe it's that imagination is more mandatory, since you need to imagine the people you come in contact with, the ships in combat, and so on, I'm not sure.
So it makes me sad to post a bug. Really. What makes me even more sad is that I'm away from my "play computer" now and have to do the same thing I (as a software engineer) hate to see users do: post a "sometimes" bug with few specifics.
Sometimes, when I tried to save with different names over and over in the same slot on the Quine4000, the game would object... telling me that too many files were open, and giving me an error code, but I can't remember that code now. "\0", maybe? Does that help?
I'll try to remember to write down more specifics on this bug if I see it again. If there are contents of a particular file that might help, let me know, and I'll try to collect that, too.
Again, amazing work! In Pascal, yet! You have my awe and respect, sir!