Because you essentially asked a meaningless question. I personally know of only one (useful) computer program that is totally stable and bug-free: TeX. There might be others, but you can bet your sweet unmentionables that no modern operating system is totally stable. In fact, the only reason TeX is stable, is because it only does a few, selected things (it does them very well, mind you).

So, instead of demanding a stable O/S (which is bollocks), you could have asked a useful question, like: "Is <insert most loathed bug> still present in the latest incarnation of ITOS2006/ITOSHE2007?"

Now, if your 770 crashes several times a day, one might start by asking if it always crashes when using a particular application, or if those crashes are truly random. If the latter is true, it might be a good idea to return it to sender for fixing; unless you were one of the earliest adopters or are living in an uncivilized part of the world, your warranty should still be valid.

If it's the former, well then don't use that application anymore.