Mike Hyatt watched a presentation melt down due to technology failure (and non-presentation-savvy tech help). He offers some great advice for dealing with such situations. Read the whole thing, but I’ll reproduce one piece of his advice that would be good to keep in mind for any sermon, no matter what the source of the interruption:

Apologize once, then stop apologizing. My only complaint with the speaker whose equipment failed yesterday was that he kept apologizing. I know how embarrassing this can be. You want to find a hole and climb into it. It is humiliating. But the audience will take their cues from you. If you are calm and at ease—even if you have to fake it—they will be calm and at ease. I think a good rule of thumb is to apologize once, then zip it. Don’t bring it up again. Let the techies do their job and, hopefully, get it fixed…

I know this is a huge issue for me in more than one way. I think you have to keep a couple of things in mind.

1. If God accepts you you can afford to stop worrying about what your congregation thinks. I realize at some level at at some time you may need to think about it, but it never helps to be anxious about it when you are still in the middle of preaching. It is irrational to let anxiety about what you can’t control ruin what you can control. And the congregations is a lot less likely to “move on” if you won’t. So I think in many cases, when we do this, there is something else going on. If we talking to get confidence rather than because we know we’re doing what we’re called to do, then we’re going to find it hard to deal with public screw-ups. Remember, our praise is from God not from men. Justification by grace alone isn’t just what you preach, it is how you preach.
2. While not being sure of where you stand can be a “negative problem”–lacking assurance of acceptance–there is also a “positive problem” that besets all of us: we worship ourselves. Public mess ups that are either our fault or even that are not but that take away our perceived controll over our self-presentation are direct blows to our idol. This is the perversion of a proper confidence in our calling and the position God has graced us with. If you find yourself worrying when it obviously only hurts the very thing you care about–your presentation–then maybe some self-searching and some repentance is in order.

(By the way, I don’t mean to be harsh, but nervousness is not always a sign of humility. It can be a sign that you care too much about the wrong things. This is not always the case, and people who are not gifted at speaking may understandably be nervous for perfectly ordinary reasons. I would be nervous if forced to do something I don’t believe I’m called or equipped to do! But it is worth considering in some cases if you care more about what people think then what you’re supposed to tell them and for Whom you are speaking.)