Yet another activation problem

I have DS installed on a number of systems in our environment  (Windows 7), but I have one user out of about 50 that cannot seem to get the program to activate.  At first, it was not sending him an activation email after entering his info, so I uninstalled and reinstalled the application.  This time, he did receive the email, and it stated that actvation was succesful after clicking on the link.  However, when he opens the program, it still asks for his email to activate every time.  I've been searching this forum, but have not found any help with this issue.  Any suggestions???