Ah, I'm testing on 7.41 and it seems that the checkbox has moved to Alt+O -> Other in the last few versions. It *might* be related to a bugfix in which that checkbox doesn't actually work in the version, but I'm not entirely sure. In any case, if you close mIRC and have the same check=0 setting in your mirc.ini, and it still doesn't work, there definitely is a bug around the dialog in 7.29.
Hate to say it, but the ironic solution here might be to update. It will be the last time you would have to do this, since I can confirm that at least in 7.41, the checkbox does (now) work. For what it's worth, 7.29 and 7.43 should be completely compatible with one another, and there are very few aesthetic changes that should affect your experience or scripts-- it should effectively be a completely unnoticeable change.
