[sunny bonobo]

If you are trying to sign up as a new account, but with your old email address, then they are probably blocking you based on that email address.
*******
Thanks. I tried a new email address.

[flamberge]

To break common "fingerprinting" methods that identify your computer, any one of the following techniques may work:

1) Change browsers.

2) Change the "do not track" setting in your browser. If it is "ON", turn it "OFF". And vice-versa

3) Install a new font to your computer.

4) Change the screen resolution to a different value.

5) Change the font scaling from 100% to some other value.

6) Remove or add a new plug-in to your browser.

Changing any one of these items may change your computer "fingerprint" and make it look like a different computer to the trackers.

As others have mentioned, you also need to clear all cookies from your browser.