Scheduled tasks in Win XP

I am using winXP, single user and for that single user I do not enter any password.
When I schedule one task, when it is due it did not run and says : The scheduled task did not run because user account password was not entered. Isn’t no password apassword? How can I enter a password that does not exist? Does that mean that I have to assign a password to my user account to run scheduled task?