This question already has an answer here:
As a follow-up to this question, I am wondering how much care I need to put into my Windows login password, for when I leave my computer alone in "sleep" mode. (I know that Windows passwords can be easily removed.) Is there any software that can try to crack the password from the lock screen? Or do I just need to have a login password that cannot be defeated in, say, my hour-long lunch break?
There is a related question about the Windows screen saver password; I would guess that the lock screen is controlled by different logic.