Has anyone else experienced this? Once I have over 30.000 gold after collecting taxes, there appears a "-" in front of it (say, "-32062"), and my gfold counter drops to 0 a second later. Or has it nothing to do with the amount that you own?
Needless to say, as it happens in the latter part of the game, there is no way I can compensate for the gold so quickly.

It sounds like the game uses the data type smallint/short int which is 2 bytes large with maximum value 32,767 and minimum value -32,768. I guess they cared a lot about size of the variables when the games were distributed via floppy disks.

That must be it. OK, now I will try to waste my money fast before my taxes come in and raise me above the magical 32767.

Yup, I can confirm this.

For anyone who's wondering, the way it works technically is, 32,767 +1 = -32,768 (the minus sign is stored in the same bit that needs to be set to store value of 32,768).

Being an experienced old time gamer (who occasionally cheating with hex editor on saves or even mod games itself that way) I'm on lookout for those *magical* values of data type maximums that can give you lot of trouble. Normally, you only run in this sort of thing when going far out of the intended design ranges of some values (even in modern games), but in Castles 1 it is surprisingly easy to reach that during normal play.

There indeed nothing else you can do about it, just try to make sure you won't roll over that sum at any time.