This is just my diagnosis on what happened. As I paint cars for a living.
The clear coat you put on is overtop of a laquer based paint, the underside doesnt dry while the top side does giving you a milky appearance, thus also giving a beading effect.
Sanspapering it off wont be an easy task, what you will need to do is sand in layers and keep letting it dry untill its completly removed.
It would almost be easier to thinner the paint completly and start over. next time making sure all the paint stays one consistant type of paint. Enamel, Laquer etc.
Did you get it fixed... I just noticed this post was a little old