Joan has an HP computer running Windows 7, but she wound up with something on her system. Leo says that chances are she went on Download.com to install software and it's installed adware on her computer. Leo says that Microsoft displays a message if she wants to remove a system file, which may be what she's trying to do to remove that adware. On Microsoft's UAC popup asking to update the system file, Joan should say yes.
Also, from now on, she should run as a standard, or limited, user instead of Administrator. That way she'll have to input the administrator password every time something wants to be installed.