Getting 'z' on the login page as well as user tries to login

[Adixit]

Hi,

I have configured Testlink and it was working well but suddenly I am getting message 'z' on the top on login page as well as when I enter user name and password I get the same message with a blank page so nothing is working for me , any idea?

Thanks

Amit

[havlatm]

Check configuration file for invalid character (especially at the top and last line).
Set clean installation definitely helps.