So what do you do?

This tweet by Michael Arrington says it all: investors are human, take it slowly and answer the very first thing what is on their mind: what is it that you are actually doing. You might have been working on this startup for months now, an investor hears about it for the very first time. You suffer from the Curse of Knowledge, and remember, an audience who is guessing what you do in the back of the mind is not paying attention to all the other things you want to say.

Just read an entire investor presentation, twice, carefully. No idea what this company wants to build or sell.Maybe sensors. We'll see.
— Michael Arrington (@arrington) March 21, 2012

Michael tried reading the deck twice, most investors will not do that.