FIND:

 NOTE --- There's no explicit action to take place here. This FIND is just aimed to point you to the right place the next action.

	//
	// Obtain a list of topic ids which contain
	// posts made since user last visited
	//

FIND:

	if ( $userdata['session_logged_in'] )
	{

REPLACE WITH:

	if ($userdata['session_logged_in'])
	{
		// 60 days limit
		if ($userdata['user_lastvisit'] < (time() - 5184000))
		{
			$userdata['user_lastvisit'] = time() - 5184000;
		}