I've realized after a few months of using our new Crestron room control systems in our videoconference rooms that people are still not "getting it". Even though information is contained in three simple pages, users who have not been trained cannot perform simple tasks like show the document camera or play a DVD. The only solution is to redesign the user interface to get right down to the basics and eliminate anything that is not absolutely necessary to get the job done. Fewer controls, bigger buttons, plain english command descriptions, etc.
Here's a good link to some theory on good user interface design: http://www.useit.com/papers/heuristic/heuristic_list.html