In my experience with Sencha/ExtJS4.0.2 framework, i am faced with a problem with the garbage collector which is run automatically every 30s stops JS execution in my IE8 / WINXP.

The following JS error apprears randomly:
Error occured:
Message: ‘events’ is null or not an object
Line: 10708
Char: 9
Code: 0
URI: http://localhost:8080/qe2web/extjs/ext-all-debug.js

The solution is to disable the Ext garbage collection by:
Ext.enableGarbageCollector = false;

Note: I have placed this code in:

	name: 'qe2web',
	appFolder: '/',
	controllers: getControllers(),
	launch: function() {
		Ext.create('Ext.Viewport', {....} );
		Ext.enableGarbageCollector = false;