Yeah, sorry about the ambiguous question. If I knew what the problem was, I might have been able to solve it.
By repeatedly cutting code and running to see what worked, I learned that the error was originating with a specific if-statement being called within the dialog. If an integer variable was greater than -1 and another variable was less than 1, then a specific message was to be displayed.
No idea why this specific statement was causing crashes, when other identical ones ran perfectly. It will remain a mystery to me. But in my frustration realized there was a more elegant way of re-writing the entire puzzle, with the added bonus keeping it a lot more logical for a player to solve.
Moderator, by all means delete or lock or whatever it is that needs to be done. Apologies.
KB