Jooel - its could one of maybe couple things. Kixforms can cause a stack overflow (the only time i've ever seen it happen is during development when I've screwup the window classes) ... or a script can stack overflow though recursion (which your not doing) ... or maybe more likey, some "resource" is being used-up and not freed properly - little fuzzy on that last one, but it could be many things.

If Kixforms stack-overflows ... you usually see it right away - even before the form displays ... something that takes hours to crash sounds more like something slowly being eaten away at - and then crashes ... don't know what that "thing" might be though ... lets keep our collective eyes on it though.