You've just connected to your Small Business Server (SBS) via the /remote site, looking for Remote Web Workplace and get a warning at the bottom of the browser that the add-on is disabled. When you click on the add-on list the Remote Desktop (RDP) control is missing.
Ramesh over at winhelponline has the answer, you need to delete this registry key:
Then close Internet Explorer and restart. Worked a treat for a client using an IdeaPad S10e with Win XP Home and IE8.