I have been in contact with two of the Admins on the CMNH Forum. I found out that if you get a blank page or Error 403... forbidden, it might be a lockout.
Once they unblock your IP, you should be able to login. If you have the correct username and don't have your password, you can click on "forget password" and reset it to enter the website. (As MAK noted in her post, you may have to delete your cookie).
~Joyce
YIPPEE!! Thank you, Joyce, for taking the time to hunt someone down at CMNH! Don't know why they never responded to my original report, but that's water under the bridge...