More Manchu CTD experiments:
I'm begining to doubt my original theory that eep_mch 221000 and major_mch 10024 conflict. When I deleted 10024 and left 221000, the game did not CTD, but then 221000 didn't fire either. When I delete 221000 and leave 10024, the game does *usually* CTD. However, the CTD comes only several days after 10024 fires. Hence, the event fired Jan 28, 1683, but the CTD comes on Feb 1.
One thing I noticed playing as Manchu - in several tests, as soon as I became China, a new Manchu revolted. This is because the revolt file gives 1820 as the MCH deathdate - this should probably be changed so that once the Manchus have taken over China, they will no longer revolt. A deathdate of 1682, for instance.
However, I can't explain the CTD this way - why a CTD because a revolter appears?
Unless, that is, the sudden & unexpected reappearance of Manchu triggers an event which was not written with this possibility in mind.
Now, I've gone through both the MCH and CHI event files and I haven't found an event which would trigger on exists = mch at the wrong time. So I'm begining to wonder if the real problem isn't in another country's events - a neighbor maybe, with an event triggering on exists = mch which fires when the "Neo-Manchu" revolter appears and causes a CTD.
An event triggering on this revolter's appearance would explain why the CTD comes frequently but not always: the revolter is a contingent possibility, followed perhaps by an event choice which creates another contingency, leaving some chance that the CTD will not occur.
Nevertheless, to test this theory one would have to comb through all the Far Eastern countries' event files. I'm afraid I am not the one - I don't know these files at all, and I don't have the time to educate myself.
However, perhaps the people who have worked on the Far East set-up can remember if there are events for other countries which trigger on MCH or might otherwise be the culprit.
One last point - virtually the only solid conclusion I can offer is that the problem stems from Manchu becoming China. 10024/221000 are not the cause directly, but clearly the CTD problem begins with these events, especially 10024.