ZAI installation problem

I'm trying to install ZAI 7.5 but the installation process always fails during the MSSQL Server 2005 express installation with the following error message:

SQL Server Setup could not validate the service accounts.
Either the service accounts have not been provided for all of the services being installed,
or the specified username or password is incorrect.
For each service, specify a valid username, password, and domain, or specify a built-in system account.

Installation type: standalone deployment / inital installation
OS: Windows XP Pro (virtual machine) with latest patches installed

Do you have any solution?

J. Simon