First, Verify that you are using the correct username and password. (If you are using your original SAM information, there should be NO caps, and NO spaces.) Then make sure that you are typing correctly, and that the Caps Lock is not on. If it still will not let you logon, delete your cookies and Temporary Internet Files by going to Tools, Internet Options (in Internet Explorer), and clicking on the buttons that say "Delete Cookies" and "Delete Files" (this may take a while).
This problem occurs when cookies are disabled in your browser configurations. To Correct:
Check system requirements, and verify that you computer is fit to run WebCT successfully.
Run the Browser Tune Up to check for compatibility errors, or missing plug-ins.