Normally, I don't get frustrated at games, I usually breeze through them, but Witcher 2 is giving me real trouble, and at the very beginning, where you're running from the dragon. It won't let me use potions, and I keep getting burned no matter what I do. Help?

You can only use potions before battle when you are meditating.

Try avoiding the fire by staying with your group and dispatching the mobs together...don't run in front.

Use the quen sign.
It immunizes you against the breath attack and the breath doesn't whittle down quen's duration.

Use Quen when moving through the fire. Let your companions kill or distract some of the guards and enemies. ALWAYS DODGE AND STAY AWAY FROM GROUPS.

That's strange. I always stuck with the group and still got flamed, but I'll try using the Quen sign. Typical that it doesn't tell me its effects in-game. :/

Somewhat counter-intuitively, the game only tells you what signs does when you cast the sign for the first time.

With Quen sign on, you will still get damaged by the dragon fire (guess it absorbs physical damage but not fire damage) but you will not be incinerated (the DoT hurts a lot).

Some notes:
1. The building will protect you as long as the roof does not fall off completely. Even if it is on flame, if you can't see the sky that means you are still safe from the dragon fire.

2. Stay behind Triss or get out of her way. Her fireballs can hit you. Although it does not damage you, it can knock you around and you might mistake her fireball to getting burned by the dragon.

3. To run from first structure to second structure without getting burnt,
a) Dispatch the first 3 guards.
b) Note that each structure has 2 parts. Run to the forward part. If the roof has not been burnt through, wait there and look to the left when facing the second structure.
c) At one point you will see the dragon just outside trying to burn the building. The roof will take a while to burn through. After a while, the dragon will dive downwards out of sight.
d) Run to the second structure like a son of a gun!