Is your browser auto filling in your login details? I ask because most modern browsers auto save your login and it may be filling in the login box with a previous password.It's making me change my password on every visit. Therefore I have to watch an advertising video to get a new password.
Do you have another computer you can try logging into the site from? I only recommend this option to see if it works from another browser, which will see if it's your browser or every browser you login from.
If you continue to have problems, please send me an email - [email protected] - and I'll help you get it resolved.