The security ID did not match

Hi,
I have the message:
"The security ID did not match. The request was terminated to prevent a security breach. Please try again." even after refreshing the browser page!
while the joomla login menu link is working properly.
How to operate this module?
Regards

HI,
I have both a sclogin module and the joomla login page. Could this be a reason?
I wonder if I keep in parallel the joomla login page with your login module. What do you recommend?
Regards