Thanks for your help, I've done a few changes to the 'run' method and still
I have the same problem, I've been testing this code for a while and it
seems like while the 'run' method is running the 'paint' method is called
many times. the 'paint' method reads 'scanning' as FALSE, while 'run' is
running and 'scanning' have got the value TRUE inside 'run'....

package com.test;

import javax.microedition.lcdui.*;
import javax.microedition.lcdui.game.*;
import javax.microedition.media.*;
import java.io.IOException;
import java.io.InputStream;
import java.util.*;
import javax.microedition.io.*;

class testManager extends javax.microedition.lcdui.game.LayerManager
implements Runnable
{
   public boolean scanning = false;
   public testManager(int width, int height) throws Exception {
   }

   //Methods
   public void paint(Graphics g) {
       synchronized (this) {
           if (scanning) {
               System.out.println("TRUE");
           }
           else {
               System.out.println("FALSE");
           }
       }
       paint(g, 0, 0);
   }

   public void Scan() {
       strInfoText = "helloworld3";
       synchronized (this) {
           scanning = true;
       }
       Thread thread = new Thread(this);
       thread.start();
   }

   public void run() {
       synchronized (this) {
           if (scanning) {
               for (int i=0; i<10; i++) {
                   System.out.println("TESTING " + i);
               }
               System.out.println("scan done");
               scanning = false;
           }
       }
   }
}

This code generate this output to the debug window....
The FALSE are written by the paint method.....

FALSE
FALSE
TESTING 0
TESTING 1
TESTING 2
TESTING 3
TESTING 4
TESTING 5
TESTING 6
TESTING 7
TESTING 8
TESTING 9
scan done
FALSE
FALSE
FALSE
FALSE
FALSE

But when I modified run, removed this statement:
scanning = false;

Now the result gets as shown below

FALSE
FALSE
FALSE
FALSE
TESTING 0
TESTING 1
TESTING 2
TESTING 3
TESTING 4
TESTING 5
TESTING 6
TESTING 7
TESTING 8
TESTING 9
scan done
TRUE
TRUE

In my humble opinion this means that this statement :
synchronized (this) {
   scanning = true;
}
works okay....

BUT, while the 'run' method is running the 'paint' method is called many
times. the 'paint' method reads 'scanning' as FALSE, while 'run' is running
and 'scanning' have got the value TRUE inside 'run'....

What must I change so that the 'paint' reads the value 'scanning' have while
'run' is running?

Jeff