Example 2
An astronaut, a guest speaker at local elementary school spends half an hour trying to connect his laptop to the school's projector, only to eventually give up in frustration. The students missed out on cool space-flight pictures and first-person narrative, and the speaker had to improvise on the spot, and try to describe things the students had never seen.
To avoid this problem, see if your location will let you do a run-through a day or two before. If not, make sure you arrive early to set up so you have time plenty of time to troubleshoot if necessary.
Most importantly, always have a backup plan. Be prepared for a failure of technology--for example, you could write bullet points on the white board as you talk instead of running the PowerPoint. You could bring backup flipchart paper and an easel--just in case. Whatever you decide to do, just make sure you'll be able to cope in the event of unforeseen events.
Bottom line
Your presentation should always be strong enough that you could close the deal even if you left your laptop on the airplane, your flipcharts were burned by acid and the dog ate your notes. Make sure you have a plan B, and come prepared to adapt to whatever glitches occur.