I don't get why this is happening. I have to write in special characters, you know the string of letters you have to write in for security reasons, eg. when signing up for a Gmail account. I get this all the time now when I have to log in, it happens after I write in my password. Does anybody else have this problem? And what can I do to stop it? Thanks in advance

Yes, I guess this happens to everyone (captchas). Google tries to prevent malicious mass-supscriptions or similar by bots...