When i plug my iphone into my laptop then turn it off it says its disconnected why?

Ok so i usally plug my ipod into my laptop and turn it off and it usally says its still connected but now i have a new laptop and when i turn it off it says its dissconnected my laptop is a windows 7

It is very likely that your hold laptop for some reason kept power on it's USB ports when it was turned off. This is usually an unintended problem as it would waste power when the laptop is not in use. You'll just have to keep your new laptop turned off.