Microsoft recommended using the Windows XP recovery console to boot the system and then accessing the "%windir%\$NtServicePackUninstall$\spuninst" folder.
Once in the folder, engineers had to rename "spuninst.txt" to "spuninst.bat" and execute the batch command "batch spuninst.bat." When that process was completed, a rollback of the Service Pack file should have occurred. That didn't happen. So the batch file had to be executed a second time, and then access to Windows XP was restored--but with some caveats. Once back in the Windows operating system, Test Center engineers had to open the registry and set "HKLM\System\CurrentControlSet\Services\RpcSs\ObjectName" to "LocalSystem." Next, engineers executed the "windir%\$NtServicePackUninstall$\spuninst\spuninst.exe," which prompted additional rollback changes to the registry.
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Windows XP
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\HotFix
Убить упоминание о любых фиксах-паках, предварительно сделав копию разделов.
Удаление пакета обновления 2 (SP2) для Windows XP.