Answer: If you keep seeing the "Login incorrect. Please try again" message after entering your user name and password, check that the user name and password have been entered correctly. Try re-entering, and watch for the correct case (the site is case sensitive - make sure Caps Lock isn't turned on).
Answer: If you see the "Your account has expired" message after entering your user name and password, you are using an out-of-date login. Get the current login information from your counselor, teacher, or whomever is helping you use CIS.
Answer: If the user name and password fields clear after you enter your info, instead of taking you to the CIS front page, it may be that the privacy setting of your Internet browser isn't allowing cookies.