WinXP Scheduled Tasks password

I am the administrator on my XP machine. I have created other users on my XP machine. None of the users has a password. I am trying to run a Scheduled Task (to run a file backup .bat job) but it will not start because of a missing or blank password. All the documentation just says that you have to use one – it doesn’t tell you what to do if your user account does not have a password assigned.

Anyone know a ‘work-around’ for this?