A few thoughts, which may not be helpful. I have > 5,000 machines using autoboot.
I use $autoboot$_departmentname
Make sure you set the account $autoboot$ so User cannot change password and Password never expires.
Don't reset password, etc. on the $autoboot$ accounts.
Sure. I have checked the prevent change password but there is something change on autoboot account.
also, you can't use SSO with autoboot - you need to make sure the appropriate Windows login options are disabled for your machines.