Originally Posted by KVS
Where exactly are you trying to use the [Ins] key?
Insert/Overwrite mode toggling that works in word processing applications (such as WinWord), does not apply to standard text input fields in Windows (e.g. it won't work in Notepad).
But it works in IE. I think that's his point . . . Firefox does everything else so well, but it doesn't replicate this behavior of IE's.