A black screen is displayed and then the system stops responding when you log on to a computer that is running Windows Vista or Windows Server 2008
A black screen is displayed after you enter your user credentials in the logon dialog box on a computer that is running Windows Vista or Windows Server 2008. When this issue occurs, you can still move the mouse pointer. However, you cannot start applications such as Windows Explorer. After a while, the operating system stops responding.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB972904.