To boot to the desktop successfully, try these following steps:
Click on F8 when starting windows.
A new menu will appears, Choose Command Prompt option when the new window appears, type (Type Enter after each command):
cd windows\system32\config ren default default.old ren sam sam.old ren security security.old ren software software.oldren system system .old cd regback copy default ..\ copy sam ..\ copy security ..\ copy software ..\ copy system ..\
After this type: EXIT and restart the system.
It will boot to the normal mode with the service pack 1 on the Computer.