The SBS Setup Computer Wizard checks:
1. UserName exists in %SystemRoot%\Users Shared Folders.
2. The account is configured to use a logon script.
To resolve the problem:
1. Create a UserName folder at %SystemRoot%\Users Shared Folders and make sure it as shared as UserName. Make sure that UserName has Full Control over this folder.
2. Make sure that the account is configured to use a logon script. You can use the Small Business Server Console by selecting Manage Users from the Tasks tab. Select the user and click Review or Change User Information. Do not change any of the user information. The wizard will check the account profile and add the necessary logon script information. You can also use User Manager for Domains.
Correcting these items should cause the Setup Computer Wizard to display the account.