Log In Problem With Ie9

I have no clue what is going here, but IE9 on a specific machine(my boss laptop). He can not log in. No username/password error. As long as he clicks sign in, Yii does the sign in thing, but then redirect him to homepage.

IE9, Chrome , FF works on my machine, but not his IE9. He doesnt want to test Chrome or FF on his machine.

My guess is his IE9 does not set cookie/session correctly. What are the possible troubleshooter steps I should take ?

Here is my main.php config


// This is the main Web application configuration. Any writable

// CWebApplication properties can be configured here.

return array(


	'name'=>'Project Eden',



	// preloading 'log' component




        'onBeginRequest' => array(

            'class' => 'application.components.behaviors.BeginRequest'




	// autoloading model and component classes





	// application components



			 'class' => 'WebUser',




		'browser' => array(

   		 'class' => 'application.extensions.Browser.CBrowserComponent',



		// uncomment the following to enable URLs in path-format











	// application-level parameters that can be accessed

	// using Yii::app()->params['paramName']


		 'languages'=>array('tr'=>'Turkish', 'en'=>'English', 'de'=>'Dutch'),