If your SP1 (Service Pack 1) installation on Windows Server 2003 fails, resulting in corruption of the HKLM\Software and HKLM\System registry hives, AND the rollback process fails, you may be able to restore these hives from the Software.sp and System.sp files that the service pack install backed up at %SystemRoot%\System32\Config.
To replace the corrupted registry hives:
1. If necessary, configure your BIOS to allow starting from a CD-ROM drive.
2. Insert the Windows Server 2003 CD into the CD-ROM drive and restart the server.
3. Press the space bar when you receive Press any key to boot from CD.
4. Press R in response to:
To setup Windows Server 2003 now, press ENTER
To repair a Windows Server 2003 installation using Recovery Console, press R
To quit Setup without installing Windows Server 2003, press F3</b>
6. When prompted for a password, type the Administrator password.
7. In the Recovery Console, type the following commands, pressing Enter after each line:
ren System System.bad
ren Software Software.bad
ren System.sp System
ren Software.sp Software</b>
NOTE: If your registry hives were corrupted before you attempted to install SP1, the .sp files will be corrupted.