Simple test plugin to trigger the WordPress issue described in Trac ticket #17626 (http://core.trac.wordpress.org/ticket/17626). The image ID is hardcoded, so you'll have to edit the plugin so it matches your upload.

wceu-test.php

<?php
/*
Plugin Name: WCEU test plugin
Plugin URI: http://core.trac.wordpress.org/ticket/17626
Description: Test plugin to trigger bug #17626
Version: 1.0
Author: Roy Tanck
Author URI: http://www.this-play.nl
Licence: GPL
*/


if( !function_exists('wceu_test_init') ){

	function wceu_test_init(){

		add_image_size( 'wceu1', 300, 300, true );
		add_image_size( 'wceu2', 300, 200, true );
		add_image_size( 'wceu3', 300, 100, true );

	}

	add_action( 'init', 'wceu_test_init', 10, 1 );

}


if( !function_exists('wceu_test_function') ){

	function wceu_test_function(){

		$img = image_get_intermediate_size( 6, array( 300, 300 ) );
		var_dump( $img );

		$img2 = image_get_intermediate_size( 6, array( 300, 299 ) );
		var_dump( $img2 );

		$img3 = image_get_intermediate_size( 6, array( 300, 301 ) );
		var_dump( $img3 );

		return '<p><img src="wp-content/uploads/2013/10/' . $img['file'] . '" alt="testimg" /></p>';
	}

	add_shortcode( 'wceutest', 'wceu_test_function' );
}

?>