You're hitting a problem about 3 or 4 other people that I am aware of have run into. In all likelihood it is a conflict with another program installed on your PC. Possibly a plug-in to Internet Explorer. Possibly even a virus or spyware of some sort. Problem is, I don't know what the issue is, and everyone that I am aware of has ultimately resolved it by reinstalling Windows, which is a pretty drastic resort.
Do you have a pop-up blocker installed on your PC? The context menus (right-click menus) use a feature of Internet Explorer that might have been at one time exploited by websites to show a pop-up, although frankly they are not well suited for that. Regardless, an overzealous pop-up blocker might be preventing the TD software from displaying the context menu.