Final answer:
The most likely cause for the system denying access with a correct password is that the Caps Lock or Num Lock key is turned on. Account lockout or being disabled by an administrator are also possibilities, while a keyboard driver issue is less likely.
Step-by-step explanation:
If a user is trying to log into Windows on a notebook computer and the correct password is being entered but the system denies access, claiming the wrong password has been entered, there are a few likely causes. The issue could be that the Caps Lock key is turned on, which would cause all letters to be entered as uppercase when the password might require lowercase. Another possibility is that the Num Lock key is on, particularly if the password contains numbers and the user is using a keyboard with a numeric keypad. This would affect the input of numbers versus letters. It's also possible that the user's account has been locked due to too many incorrect login attempts, or the account has been disabled by an administrator. A less likely cause is a malfunctioning keyboard driver, which would usually affect more than just password input.