[Plugin: WPThumb] Featured Image in admin bug

I do not have that issue on any of my active installs – maybe you can post some further info about your server?

Have the same problem on my installation. Any solution for this?

Well, to fix this :

In wpthumb.php :

function wpthumb_post_image( $null, $id, $args ) {
	$wpsize = $args;

	//.....

	list( $html_width, $html_height ) = image_constrain_size_for_editor( $html_width, $html_height, $wpsize );

	return array( $image_src, $html_width, $html_height, true );
}