I don't think the SPR tag is bugged, except that it doesn't seem to revolt (if I remember correctly). At a guess, I would say that you have an ID conflict in your 1492.inc file. No two clauses may have the same type and id; if they do the game will crash sporadically. My little EU Validator tool is able to detect most (but not all) such conflicts. Download link is in my signature.
/Doomie
/Doomie