Windows Vista Service Pack 1 or Windows Server 2008 stops responding (hangs) during startup
When you press the power button or click Restart on the Start menu to start a computer that is running Windows Vista Service Pack 1 (SP1) or Windows Server 2008, the system startup may fail. The system stops responding (hangs) and shows a black screen where the Windows logo typically appears. Additionally, the mouse pointer does not appear, and the hard disk drive (HDD) light does not flash. When the HDD light does not flash, it means that the HDD is not being accessed at that time.
When this problem occurs, you have to force the power off. Then, you must press the power button to start the computer again.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB960723.