Full sized images for thumbnails after import – slow

Hello community, I just installed a new blog and imported the data from an existing blog.

The current blog already resized the images that were included in the blog.
image.jpg
image-150×150.jpg
image-300×300.jpg
image-1024×1024.jpg

All is well other than my images, they are there, but even though the setting are the same as the existing blog and the resized images are present, it still forces the browser to load 3000+ px images!!

I added this to functions.php, but the full sized images continued to load.

// Enable post thumbnails
add_theme_support('post-thumbnails'); 

if ( function_exists( 'add_theme_support' ) ) {
	add_theme_support( 'post-thumbnails' );
        set_post_thumbnail_size( 150, 150 ); // default Post Thumbnail dimensions
}

if ( function_exists( 'add_image_size' ) ) {
	add_image_size( 'category-thumb', 300, 9999 ); //300 pixels wide (and unlimited height)
	add_image_size( 'homepage-thumb', 220, 180, true ); //(cropped)
}

Can someone lead me in the right direction?
Thank you in advance..
Aaron