Coming to work for a company like Insperity that provides full-scale HR outsourcing of functions like payroll and other HR services may mean a new world for you. As your interviewer has likely had many individuals interview before you, they know that even their top candidate will come with their own unique weaknesses. They pose this question to ensure that you are aware of any weaknesses or shortcomings that you may have and that you hopefully have a plan of action for overcoming them upon starting. Be prepared to discuss your weakness, citing why it would be a weakness, and then talk about what you will do to get up to speed quickly. However you answer, make sure your weakness is not one of the key functions of the job that may disqualify you during the interview process.