Delivery is the final and most challenging part of a presentation. Not the most difficult or the most important—that award goes to storytelling—but the most challenging, the most frightening. I never heard of slide preparation fright or storytelling fright, but stage fright is common. The reason delivery is so frightening is because it's live and it's final. You cannot undo it; once it's done, it's done.
NERVES VERSUS STAGE FRIGHT
I never had stage fright. This isn't to suggest that I was always good onstage, but I don't remember being scared. In my childhood, I was the lead singer in a children's band and coming onstage was a relatively mundane experience for me. I was nervous but never frightened. Later, I came onstage as a dancer, singer, martial arts practitioner, business trainer, business school lecturer, personal development coach, comedian, and actor. I was still getting nervous (but never to the point of being paralyzed), and I think it is pretty much normal to feel this way. Anxiety never quite goes away, and it's always worse when the role or the place is new to me.
If you have serious stage fright, one that really prevents you from speaking, I suggest you seek professional help. Scientific branches of psychotherapy (like cognitive behavioral therapy, CBT) have made some truly dramatic progress over the past 20 years. But if all you have is general anxiety, just live with it. Trust me, nobody will notice.
There are basically two ways to deal with your fear: ...