Windows XP SP3 Task Scheduler Error 0x80070005

When I try to add a task I get error: Error 0X80070005: Access Is Denied

Windows XP Pro Service Pack 3.
1 administrator account with no password!
I don't want to set password for the account because I want auto login when i start computer without entering any passwords.

Microsoft say this problem is caused by security update 841873

There is a hotfix available.

See: http://support.microsoft.com/kb/904423