I am running Ubuntu 12.04 64bit. When I get at the login screen and try to type the password for my user, I cannot type anything for about 20 seconds. After that, the keyboard starts responding and everything works fine. Mouse is responding normally as well as all buttons of the login interface (time/calendar, session selection (Unity/Unity 2D), etc.).

What could be the reason for this behavior? How can I solve this temporary freeze of the keyboard so that I can type my password immediately without having to wait each time?

Thanks for your time.

EDIT: I tried auto login, but the problem is still there: the Desktop loads but even there, if I try to type something in the dash or anywhere else, I must wait about 20 seconds before I can actually start typing. Can the issue be related to some keyboard modules that get loaded little bit "too late"?