Wordpress2.5 does not handle old type thumbnail images.
This bug will be in image_downsize() function.
original source
elseif ( $size == 'thumbnail' ) {
// fall back to the old thumbnail
if ( $thumb_file = wp_get_attachment_thumb_file() && $info = getimagesize($thumb_file) ) {
$img_url = str_replace(basename($img_url), basename($thumb_file), $img_url);
$width = $info[0];
$height = $info[1];
}
}
suggestion
elseif ( $size == 'thumbnail' ) {
// fall back to the old thumbnail
$thumb_file = wp_get_attachment_thumb_file( $id );
if ( $info = getimagesize($thumb_file) ) {
$img_url = str_replace(basename($img_url), basename($thumb_file), $img_url);
$width = $info[0];
$height = $info[1];
}
}
