Can't display image contextMenu on Linux.

Question

I'm writing an Flex 3 (same issue in Flex 2)application where
right clicking on an image should display my customized
ContextMenu. The contentMenu is NOT displayed whenever I execute
this application in Firefox on a RedHat Enterprise 4 Linux system.
This issue doesn't occur on Windows based system (Firefox or IE).
Attached is my sample application. Can anyone please help? Thanks
<?xml version="1.0" encoding="utf-8"?>
<mx:Application initialize="init(event)" xmlns:mx="
http://www.adobe.com/2006/mxml"
layout="absolute">
<mx:Script>
<![CDATA[
import mx.controls.Image;
import mx.managers.PopUpManager;
import mx.core.UIComponent;
private var square:Sprite = new Sprite();
// Image
[Embed(source="../asset/images/pie-chart.png")]
static public var iconClass:Class;
public function init(event:Event):void
square.graphics.beginFill(0000000);
square.graphics.drawRect(0,0,100,100);
square.graphics.endFill();
var newComponent:UIComponent = new UIComponent();
//must set the UI component to wrap the sprite - so set
width and height
newComponent.width = 100;
newComponent.height = 100;
var menuItem:ContextMenuItem = new ContextMenuItem("Change
Color");
menuItem.addEventListener(ContextMenuEvent.MENU_ITEM_SELECT,changeColor);
var customContextMenu:ContextMenu = new ContextMenu();
//hide the Flash menu
customContextMenu.hideBuiltInItems();
customContextMenu.customItems.push(menuItem);
var _imgObj:Image = new Image();
_imgObj.source = iconClass;
_imgObj.width = 25;
_imgObj.height = 25;
_imgObj.contextMenu = customContextMenu;
newComponent.addChild(_imgObj);
myPanel.addChild(newComponent);
public function changeColor(event:ContextMenuEvent):void
{square.transform.colorTransform = getRandomColor();}
public function getRandomColor():ColorTransform
{return new ColorTransform(Math.random(), Math.random(),
Math.random(),1,(Math.random() * 512) - 255, (Math.random() * 512)
-255, (Math.random() * 512) - 255, 0);}
]]>
</mx:Script>
<mx:Panel id="myPanel"></mx:Panel>
</mx:Application>

Answer 1

After much fiddling with display resolutions and TV setting, and several calls to Apple help, problem was found to have a really basic solution: replace the RCA connector cable. The old one was shot.