I'm more inclined that this just may be a Win10 + spaghetti coding in FFXI but...
...would there be a particular addon or plugin that would sometimes cause FFXI crash to desktop when changing characters? It's not all the time (and most days I don't get it), but it's incredibly annoying. It usually only happens when I'm logging off from a character and going to the character select screen.
If I had any dump files I'd post a pastebin.