There are 3 Possible causes for this error:
1) Most Likely - The likely cause was an invalid username or password.
Please check the spelling of your Username and Password carefully, also make sure there are NO SPACES BEFORE or AFTER the username and password.
So if your copying and pasting make sure there is now extra space being copied.
2) This message is also given when your Data subscription or license is expired or has been canceled.
3) Occasionally our data supplier will make upgrades to the data server (typically on Sunday night) this may cause the demo servers to pause for a short amount of time.