Most likely you have a case of corrupted cookies.
You will need to delete the cookies from your Internet Explorer. This can be achieved by opening the "Tools" menu and then choosing "Internet Options".
On the window dialog that appears, in the section "Temporary Internet Files", click the "Delete Cookies..." Button.
Close and open Internet explorer and try to logon.
Check this link for a graphic explanation: http://www.helpwithpcs.com/tipsandtricks/delete-cookies-internet-explorer.htm

If you've signed up and are wondering what is the status of your account

If you've signed up and have forgoten your Password