blank user name

I have noticed that when I first power up my laptop it has a blank space for both the user name and the password. However when I use a hot corner to begin my screensaver and then come back the password window, of course, is blank but my user name is already entered. Is it possible for both windows to be blank just as when i power up in the first place?

No. The reason for the way you're seeing it is because you have multiple accounts -- the login window does not know which account you wish to log into, so it leaves the user name for you to fill in.

With your screensaver, you are already logged into your account, thus it fills in your user name.