If you have created a complex password and are entering it incorrectly, you will be denied access for this reason. Upon checking your account, it is in complete working order. To avoid having to retype your password, you may choose the "Remember Me" option so that you will be automatically logged-in after your session times out due to inactivity.
You may also link your account to Facebook (if you so have an account), and use your Facebook credentials to log into the website. The only conditions where you would get this message upon logging in is if you were entering the wrong login information (most usually password). This happens to the best of us sometimes, including myself and others.
I hope that this helps answer your question...