Thats likely a result of your Internet Explorer‘s security features.
For whatever reason, this board doesn‘t work well with higher security features on most browsers, (perhaps mike will update the cookies in the future) anywho, go to Tools then Internet options and select the Security tab. If your using winXp then there should be a sliding bar to quickly adjust security levels. Bring it down to low, not all the way down but beneath half. you should be able to log into this board fine.