Image display (Image don't appear the first time?)

Question

Applet at: http://saladinsite.tripod.com/Project/MiniProject.htm
Code at and Bottom: http://saladinsite.tripod.com/Project/MiniProject.java
Hi,
I just created my very first applet. It's a simple quiz. I'll agree it's very unefficient.. but heh.. good for first try.
There is a lil problem I am having. Sometimes when I load the applet, the background image don't show up. Sometimes, the happy/cry images (corresponding to right/wrong answer) don't show up (check the applet to see what I am talkin about) It only happens once tho. It's strange. Take a look at the applet, you will see. Btw: It's not the downloadin of image that cuzes the bug. Same problem happens in appletviewer. If it doesn't appear the first time, the next time you go back to it, it will appear.
My teacher has also struggled with this problem but failed. Hope you guys can help me out.
Thanks,
Gant
LONG Code again:
import java.awt.*;
import java.applet.*;
import java.net.*;
     public class MiniProject extends Applet implements Runnable {
          boolean flag=true;
          Image happy,cry,cartoon,test,buffer;
          Graphics bufferg;
          Thread main;
               int x = 50;
               int y = 50;
               int a,b,c;
               String str;
               double score =0;
               double correct = 0.0;
               TextField txt, percent, invis;
               String boxName[] = {"Addition (+)", "Substraction (-)","Multiplication (x)","Division (�)"};
               CheckboxGroup checkGr = new CheckboxGroup();
               AudioClip RedMove, Applause, BadMove, NewGame, sad;
          public void init() {
               URL codeBase = getCodeBase();
               happy = getImage(getCodeBase(),"happy.gif");
               cry = getImage(getCodeBase(),"cry.gif");
               cartoon = getImage(getCodeBase(),"cartoon.gif");
               test = getImage(getCodeBase(),"test.gif");
               RedMove = getAudioClip(codeBase, "RedMove.au");
               Applause = getAudioClip(codeBase, "Applause.au");
               BadMove = getAudioClip(codeBase, "BadMove.au");
               NewGame = getAudioClip(codeBase, "NewGame.au");
               sad = getAudioClip(codeBase, "sad.au");
               invis = new TextField("",1) ;
               invis.setVisible(false);
               setBackground(Color.white);
               setLayout(new BorderLayout() );
               Panel p1 = new Panel();
               add("South",p1);
               p1.setBackground(Color.gray);
               p1.add(new Button("Start") );
               p1.add(new Button("Exit") );
               p1.add(new Button("Help") );
               p1.add(new Button("Credits") );
                         p1.add(new Label(" Score in (%):") );
                         percent = new TextField("",3);
                         percent.setEditable(false);
                         percent.setBackground(Color.gray);
                         p1.add(percent);
               Panel p2 = new Panel();
               p2.setBackground(Color.gray);
               add("North",p2);
               p2.add(new Label("Quiz with: ") );
          Panel p3 = new Panel();
          p3.setLayout(new FlowLayout(FlowLayout.CENTER, 25, 75));
               txt = new TextField("", 3);
               txt.setText("");
txt.setEditable(false);
               Font f = new Font("Helvetica", Font.BOLD, 36);
               txt.setFont(f);
          p3.add(txt);
          add("East",p3);
          p3.setBackground(Color.white);
          for (int i=0; i<boxName.length; i++)
               p2.add(new Checkbox(boxName, checkGr, false) );
          buffer=createImage(size().width,size().height);
          bufferg=buffer.getGraphics();
          startM();
     } //end init
          public void run(){
          while(main!=null){
               try {
               main.sleep(50);
               catch(Exception e){}
     public void stop(){
          if(main!=null){main.stop();}
     public void startM() {
                    bufferg.setColor(Color.white);
                    bufferg.fillRect(0,0,400,400);
                    bufferg.setColor(Color.black);
                         Font f = new Font("Helvetica", Font.PLAIN, 14);
                         bufferg.setFont(f);
                         bufferg.drawImage(cartoon,0,50,this);
                    bufferg.drawString("^ Click on a Quiz above to begin!", 25,47);
                    txt.setEditable(false);
                    txt.setBackground(Color.white);
                    txt.setText("");
                    percent.setText("");
                         Font f4 = new Font("Helvetica", Font.BOLD, 28);
                         bufferg.setFont(f4);
                         bufferg.setColor(Color.red);
                         bufferg.drawString("WELCOME!",15,90);
                         bufferg.setColor(Color.black);
                         bufferg.drawString("to the Interactive",55, 155);
                         bufferg.drawString("Grade 9 Math Quiz",85, 200);
                         Font f5 = new Font("Helvetica", Font.PLAIN, 18);
                         bufferg.setFont(f5);
                         bufferg.drawString("Designed by: Wasay R.",175,360);
     public void clearM() {
          bufferg.fillRect(0,0,450,400);
     public boolean action(Event evt, Object obj) {
          if (evt.target instanceof Button) {
               String butLabel = (String) obj;
                    if (obj.equals("Credits") ) {
                         NewGame.play();
                         URL url = getCodeBase(); // get url of the applet
                         try {
                    getAppletContext().showDocument (new URL(url+"credits.htm"));
                         } catch(MalformedURLException e) {
                         showStatus("URL not found");
          if (evt.target instanceof Button) {
               String butLabel = (String) obj;
                    if (obj.equals("Help") ) {
                         NewGame.play();
                         URL url = getCodeBase(); // get url of the applet
                         try {
                    getAppletContext().showDocument (new URL(url+"help.htm"));
                         } catch(MalformedURLException e) {
                         showStatus("URL not found");
          if (evt.target instanceof Button) {
               String butLabel = (String) obj;
                    if (obj.equals("Exit") ) {
                         NewGame.play();
                         URL url = getCodeBase(); // get url of the applet
                         try {
                    getAppletContext().showDocument (new URL(url+"end.htm"));
                         } catch(MalformedURLException e) {
                         showStatus("URL not found");
          if (evt.target instanceof Checkbox && flag) {
               flag=false;
               NewGame.play();
               txt.setEditable(true);
               Color c = new Color(204,204,204);
               txt.setBackground(c);
               bufferg.setColor(Color.white);
               clearM();
               handleCheckbox(evt);
               if (evt.target instanceof Button) {
               String butLabel = (String) obj;
                    if (obj.equals("Start") ) {
                         flag=true;
                         y=50;
                         x=50;
                         score=0;
                         correct=0;
                         startM();
          if (evt.target==txt && score<10) {
               String find = (invis.getText() ).substring(0,1) ;
               if (find.equals("+")) {
                         handle2();
                         paint( Create(0) );
                         txt.setText("");
                         score++;
               else if (find.equals("-") ) {
                    handle2();
                    paint( Create(1) );
                    txt.setText("");
                    score++;
               else if (find.equals("x") ) {
                    handle2();
                    paint( Create(2) );
                    txt.setText("");
                    score++;
               else if (find.equals("/") ) {
                    handle2();
                    paint( Create(3) );
                    txt.setText("");
                    score++;
          if (score==10) {
               if (correct>=5 && !(evt.target instanceof Checkbox) )
                    Applause.play();
               else if (correct<5 && !(evt.target instanceof Checkbox) )
                    sad.play();
               txt.setText("");
               txt.setBackground(Color.white);
               txt.setEditable(false);
                    bufferg.setColor(Color.white);
                    bufferg.fillRect(100,100,350,75);
                    bufferg.setColor(Color.black);
                    bufferg.drawRect(65,110,225,75);
                         Font f = new Font("Helvetica", Font.BOLD, 28);
                         bufferg.setFont(f);
                         bufferg.setColor(Color.red);
                         bufferg.drawString("Quiz Complete!", 75,143);
                         Font f2 = new Font("Helvetica", Font.PLAIN, 18);
                         bufferg.setFont(f2);
                         bufferg.setColor(Color.black);
                         bufferg.drawString( ("Your Score: " + String.valueOf( Math.round( (correct/score*100)/0.01 )*0.01 )+"%"),101,170);
                         Font f3 = new Font("Helvetica", Font.PLAIN, 14);
                         bufferg.setFont(f3);
                         bufferg.drawString("Click Start and select a Quiz at the Top to begin",19,240);
                         bufferg.drawRect(10,227,326,0);
                         bufferg.drawRect(336,38,0,189);
                         bufferg.drawRect(10,243,326,0);
                         bufferg.drawRect(10,243,0,85);
          percent.setText( String.valueOf( Math.round( (correct/score*100)/0.01 )*0.01 ) );
          repaint();
          return true;
               private void handle2() {
                    str = invis.getText();
                         Font f = new Font("Helvetica", Font.BOLD, 14);
                         bufferg.setFont(f);
                         bufferg.drawString("Correct:",15,70);
                         bufferg.drawString("Incorrect:",4,345);
                    if ( (str.substring(0,1) ).equals("+") )
                         if (Integer.parseInt(txt.getText() )==(a+b) ) {
                                   invis.setText("+correct");
                                   x+=25;
                                   bufferg.drawImage(happy,x,50,this);
                                   correct++;
                                   RedMove.play();}
                         else {
                                   invis.setText("+wrong");
                                   y+=25;
                                   bufferg.drawImage(cry,y,325,this);
                                   BadMove.play();
                    else if ( (str.substring(0,1) ).equals("-") )
                         if (Integer.parseInt(txt.getText() )==(a-b) ) {
                                   invis.setText("-correct");
                                   x+=25;
                                   bufferg.drawImage(happy,x,50,this);
                                   correct++; RedMove.play();}
                         else {
                                   invis.setText("-wrong");
                                   y+=25;
                                   bufferg.drawImage(cry,y,325,this);
                                   BadMove.play();
                    else if ( (str.substring(0,1) ).equals("x") )
                         if (Integer.parseInt(txt.getText() )==(a*c) ) {
                                   invis.setText("xcorrect");
                                   x+=25;
                                   bufferg.drawImage(happy,x,50,this);
                                   correct++; RedMove.play();}
                         else {
                                   invis.setText("xwrong");
                                   y+=25;
                                   bufferg.drawImage(cry,y,325,this);
                                   BadMove.play();
                    else if ( (str.substring(0,1) ).equals("/") )
                         if (Integer.parseInt(txt.getText() )==(a/c) ) {
                                   invis.setText("/correct");
                                   x+=25;
                                   bufferg.drawImage(happy,x,50,this);
                                   correct++; RedMove.play();}
                         else {
                                   invis.setText("/wrong");
                                   y+=25;
                                   bufferg.drawImage(cry,y,325,this);
                                   BadMove.play();
          public String Multi() {
                    a = ( (int) (Math.random()*100) )+10;
                    c = ( (int) (Math.random()*10) );
               while(c==0 || c==1)
                    c = ( (int) (Math.random()*10) );
               String a1 = String.valueOf(a);
               String a2 = String.valueOf(c);     
               return (a1+" x "+a2+" = ");
               public String Divi() {
                    a = 2*( (int) (100*Math.random() ) )+2;
                    c = 2*( (int) (10*Math.random() ) )+2;
                    while (a%c!=0)
                         c = 2*( (int) (10*Math.random() ) )+2;
               String a1 = String.valueOf(a);
               String a2 = String.valueOf(c);     
               return (a1+" � "+a2+" = ");
          public Graphics Create(int i) {
          repaint();
          Dimension d=size();
          bufferg.setColor(getBackground());
          bufferg.fillRect(100,100,350,75);
          bufferg.setColor(Color.yellow);
               a = ( (int) (Math.random()*100) );
               b = ( (int) (Math.random()*100) );
               String a1 = String.valueOf(a);
               String a2 = String.valueOf(b);
               Font f = new Font("Helvetica", Font.BOLD, 36);
               bufferg.setFont(f);
               bufferg.setColor(Color.black);
               if (i==0)
                    bufferg.drawString(a1+" + "+a2+" = ", 145,150);
               else if (i==1)
                    bufferg.drawString(a1+" - "+a2+" = ", 145,150);
               else if (i==2)
                    bufferg.drawString( Multi() , 145,150);                    
               else if (i==3)
                    bufferg.drawString( Divi() , 145,150);
                    return bufferg;
     private void handleCheckbox(Event evt) {
          Checkbox cb = (Checkbox)evt.target;
               String str = cb.getLabel();
               bufferg.drawImage(test,0,50,this);
               if (str==boxName[0]) {
                    paint( Create(0) );
                    invis.setText("+");
               else if (str==boxName[1]) {
                    paint( Create(1) );
                    invis.setText("-");
               else if (str==boxName[2]) {
                    paint( Create(2) );
                    invis.setText("x");
               else if (str==boxName[3]) {
                    paint( Create(3) );     
                    invis.setText("/");
     } //end handleCheckBox
     public void update(Graphics g){
          paint(g);
     public void paint(Graphics g) {
          g.drawImage(buffer,0,0,this);
}//end class

Answer 1

Its not easy to follow your code without the [ code] +[ /code] tags and your link may as well not be there, the code one. I would resolve this by reducing the overhead ie: stripping down the code as much as I could and then adding them back one by one. DIVIDE and CONQUER!!!
1. Take out the audio data (I suspect this may be the key problem)
2. Take out the Thread 'main' and have an actionListener attached to your answer field to handle the changes
3. Take out java.net and your URLs
4. use a MediaTracker and WaitForAll()
5. Strip it down further - AS MUCH AS YOU CAN (you can easily reassemble it quickly again) and then look at the program flow
6. Add more boolean logic to give you control over all your elements ie
if(myAnswer==answer) smiley=true;
else smiley = false;
// or whatever, as I said I could only scan through your code as it is difficult to read in its present format.
Finally: this is good work I like the smileys and the instant %'s, the general layout, good /intelligent use of random() to generate different Q's each time. It's a good application, just remember that applets can be unreliable and I think your basic problem is that you have too much data here.
Strip it right down, focus on your logical flow and then put back the elements one-by-one