I attended a meeting last week where one of the speakers was going to talk about and demonstrate her VOIP product. Shortly before she was to start her ten-minute presentation, her assistant hooked up the phone equipment and it began to boot up.
She had planned on calling a colleague to demonstrate the phone's video capability and had scheduled the call for a certain time. As she went through her presentation, the phone continued to boot. She paused... she hesitated. The phone was still booting. She came to the end of her ten minutes and was still unable to make the call.
The meeting continued on with other speakers and other business and, in the end, she had to wait until the meeting was over to show the phone to anyone who could stay behind.
The unfortunate results were that:
1) She was unable to present to the whole group
2) The phone ended up looking like a troublesome product
3) She ended up looking like she didn't know her product very well
This could all have been avoided with proper preparation. Instead of booting up the equipment right before the presentation, she could have hooked it all up right when she arrived to make sure it was working properly.
Planning and preparation are not the most glamorous aspects of presenting, but without them, you are taking a big risk with your presentation.