The following code:

		// reset select if it is the default "*"
		if(is_string($this->q_select))
		{
			$this->q_select = array();
		}

Should be moved above this if block:

		if($cols === false)
		{
			$obj = new IgnitedQuery();
			$obj->q_parent =& $this;
			$this->q_select[] =& $obj;
			return $obj;
		}

to ensure q_select is a valid array. The current implementation throws a PHP warning and is unusable.

Cheers,
Stan