What is the cause where .Xauthority-c is generated to block the authentication?

[jupiter]

Hi,

I am running CentOS 6.4. I have some first time user logged in to my
system, it did not just create a user home directory with .Xauthority,
but generated another .Xauthority-c. Every time when the .Xauthority-c
is coming, the user failed authentication until the .Xauthority-c is
removed.

Could anyone help me to understand, what caused the .Xauthority-c to
be generated? And how can I fix the system to never generate the
.Xauthority-c?

Thank you.

Kind regards.