I'm guess your pulling too hard on your bars causing your front wheel to lift. Where you have your hand on the bars is also an issue, you want them just below the midpoint of the curve. You could also be too far back when sprinting or just not have sufficient control.

You need to practice sprinting so that your hands and weight are in the right place and you can turn on the speed with control. Trying running some whistle jumps/sprint intervals where you practice going from a slow pace to sprinting as fast as you can. Try some in the saddle and some out.

However, I'm not an expert and you may be better off asking this in the track specific sub-forum. Just my uninformed two cents.