Small Java Applet freezing web browser

I am curious if anyone can help point out what I am doing wrong. I
assume I am not clearing a resource correctly which is causing the
hangup. I am just experimenting with applets right now and decided to
make one that does projectile motion for practice.

About 9 out of 10 times the applet runs, I have to force quit the
browser to get it to close (jsp server is linux tomcat, desktop is
windows XP IE and mozilla).

I appreciate the help.

package applets;

import java.awt.*;
import java.applet.*;

public class ProjectileAnimation extends Applet {
        double Xo = 0.0;
        double Yo = 0.0;
        double Vo = 0.0;
        double x = 0.0;
        double y = 0.0;
        double theta = 0.0;
        int t = 0;

    public void init() {
        setBackground(Color.white);
    }

    public void start() {

    }

    public void paint( Graphics g ) {
        Vo = Double.parseDouble(getParameter("Vo"));
        theta = Double.parseDouble(getParameter("theta"));
        g.setColor(Color.black);
        g.drawLine(0,0,0,410);
        g.drawLine(0,409,710,409);
        while ((int)Math.round(y) >= 0)
        {
                x = Vo * Math.cos(Math.toRadians(theta)) * t;
                y = .5 * -9.8 * Math.pow(t, 2) + Vo * t + Yo;
                y = 500 - y;
                g.fillOval((int)Math.round(x), (int)Math.round(y), 5,
5);
                t++;

                try
                {
                        Thread.sleep(1000);
                        Thread.sleep(0);
                } catch (InterruptedException e)
                {
                }
        }
    }

    public void update ( Graphics g ) {

                paint(g);

    }
}