If you have given enough powerpoint presentations, at some point you are going to have problems. I hope it does not happen to you but I think guarantee that it will happen eventually.
A bulb may burn out, your laptop might run out of power, something might not be compatible, or maybe a slide will not advance. The truth is that problems are inevitable and you cannot control all of them but you need to control how you react to them. In the worst case scenario, you fall apart in front of your audience and that is what they remember most out of your presentation, or maybe you spend so much time apologizing or looking embarrassed that they start to feel sorry for you. But you do not want sympathy from your audience- you want them to be focused on your messages.
Here is my advice: you have to learn how to just get through it without causing too much distraction to your audience. Of course if the power goes out and everyone is in pitch black darkness then obviously you have to address the problem but if there are smaller issues such as a computer freezing up or any compatibility issues, you have to keep going.
Remember: nobody is there for your PowerPoint presentation- they are there to get ideas from you that could possibly help them or interest them. I have faced many such situations where I accidentally unplugged my laptop or it freezes. What I would do is divert the attention of the audience from the particular issue at hand. I would continue talking, walk around the room, and toss a question out to an audience member. While everyone is busy looking at that person, I would reach down and plug in my laptop again or troubleshoot it. In this way, the audience has no idea of my problem and they are not distracted by it.
So while you cannot control any problems you might face during a presentation, you can control your reaction. Do not panic or try to apologize or even talk about it unless absolutely necessary .