A the add-on installed by Microsoft's Windows security update has only affected users of Mozilla's Firefox web browser.
B Microsoft's update had been widely announced prior to its installation.
C the Microsoft .NET Framework had been updated before although a great number of users had not realized it.
D Microsoft's "service pack" for the .NET Framework solved a variety of problems that had been overlooked before.
E Annoyances.org specializes in detecting Windows security problems and reporting them to Microsoft so the company can work on them.