One question that people often have with the story of Moses and the deliverance from Egypt is the hardening of Pharoah's heart. It seems wrong that God would do that. Let me give you a couple of ideas as to why that is...
First, I think the hardening of Pharoah's heart is a natural process that we've all seen (in our life or others). People know what the right thing to do is but they ignore it. At first they feel guilty but over time the guilt wears off and they become apathetic. They really don't care if their behavior is right or wrong. Their poor moral choices cause a slow hardening of their heart. They indict themselves and incur the "judgment" of the consequences that often follow their choices. So the Bible might frame the story as "God hardening Pharoah's heart" (because the writer wants to show God's sovereignty) but I also think it has a lot to do with Pharoah's choice.
Second, the writer (as I just noted) is trying to communicate something to us about God. The writer wants us to know that God is in control and we never have to worry about evil shutting God and his purposes down. Nothing can thwart God's kingdom and his purposes on earth...even the most wicked king on the planet is like putty in God's hands. God will even harden his heart if necessary. But note that Pharoah had more than enough time to change his mind. His heart didn't begin to harden until after he had refused to obey God.
I think one reason people wonder about Pharoah's hardening is they fear that God might harden their heart and they will be left out. I think that should concern us all to some extent and motivate us to never turn a deaf ear to God. You never know when you will stop caring. But I always tell people that if they are worried about their heart being hardened it's not hard yet! If your heart was hard toward God you wouldn't care. The fact that people are asking the question tells me that they are still interested in God.
If you want to hear more of this discussion come out to the Wednesday night class at the church building (6:45pm). The text and audio from Sunday's sermon on Moses should be posted some time today.