Why Can't I Log In?- Password Confirm Refreshing

I have had a problem for a few months now and have not been able to get an answer. Whenever I try to log in, the "confirm password" screen comes up. When I confirm, the page only refreshes to the confirm password screen. I have tried everything that I can possibly think of, but it does not seem to be working. I have played around with cookies, deleted excess programs on my computer, run a virus/spyware check and more. Oddly, if this means anything, the same thing happens to me on Facebook.

I am running Firefox 2.0.0.14 on Windows XP Home Edition SP1. I have also tried with I.E., and the same thing has happened there (not a surprise, since it is I.E.) Anyway, I have searched the web for an answer to this problem, and I have still not been able to get an answer.

Thank you in advance for any help, and thank you for looking over my problem.