Of course no operating system is perfect and people who tell you that theirs can never ever crash are lying However some operating systems can be so stable that most users never see their systems crash even after several years

What is the correctly punctuated version of this sentence?
Of course, no operating system is perfect, and people who tell you that theirs can never ever crash are lying. However, some operating systems can be so stable that most users never see their systems crash, even after several years.