If you were a software engineer you'd know that no complex software is 100% bug free. Never.
Well, I *am* a software engineer, and I'm tired of the old "software-is-complex-it's-never-bug-free" excuse. We all know software is complex. But it's not a get-out-of-jail-free card, you execute honest due-diligence in testing, take responsibility for your bugs, notify your customers about the serious ones (like, ones that involve people's money), and correct them in a timely manner.