Occasionally, Internet Explorer has an inexplicable "cookie" problem. If you still can't log in, go to the "Tools" menu on the upper portion of your browser, Click "Internet Options", then on the General tab, under Temporary Internet Files, click Delete Cookies... (click OK) and/or click Delete Files...(leave "Delete all offline content" unchecked and click OK), Click OK at the bottom of the Internet Options Window. Exit Internet Explorer and relaunch your browser and then you should be able to log in.