How do I Stop XP Reseting to Default

Over the last month I have had 10+ computers all running on XP Pro in different locations all create a new default administrater setup and require that I reset up email and programs. They clear the Desktop, Office2007 toolbars, Email and others. I have never had this in the time I have worked with XP and now 10 in one month. As long as I have a outlook backup I can recover but it all takes time. Has MS updated something that requires a reset or what.