Restoring Your System Using the ERD

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When you use the ERD to repair a damaged Windows NT Workstation, the procedure essentially reinstalls the sections of the operating system that are required for your particular setup. The data that you copied to the ERD contained in the Windows NT Registry determines which files need to be replaced, and how the configuration should be re-established.

Among the things that the ERD does are the following:

• Runs CHKDSK to determine the validity of the partition containing your Windows NT system files
• Determines whether the individual files on a system partition are valid, as determined by the use of a checksum
• Restores missing or corrupt files from your Windows NT installation disks
• Replaces your default system and security Registry hives
• Replaces the Security Account Manager hives
• Reinstalls the files responsible for booting your system in the Boot Loader: boot.ini, NTLDR, ntbootdd.sys, and ntdetect.com.

Before you begin to restore your system, make sure you have your Windows NT Setup floppy disks handy. If you can’t find those disks, you can create them from the installation CD by using the WINNT /O or the /OX switch. You can find online documentation for the WINNT.EXE program in the Help system.

To restore Windows NT Workstation on an Intel x386 system, complete the following steps:

1.	Insert the Windows NT Workstation Setup boot disk into your floppy disk drive. (Make sure your system boots from a floppy disk first.)
2.	Turn on your system, and then insert Setup Disk 2 when asked. Press the Enter key.
3.	Press the R key to perform a repair.
4.	Press the Enter key to mark any options that you wish to restore, press Tab to move to the Continue button, and press the Enter key again.
5.	Press Enter to detect devices.
6.	Insert the Setup Disk 3 into your floppy disk when requested.
7.	Insert additional disks with device drives when the Other Disk option appears, and then replace that (those) disk(s) with Setup Disk 3 again.
8.	Press Enter and insert your ERD when requested, and then press Enter again.
9.	Press Enter to select each Registry hive you wish to restore, and then move to the Continue button and press Enter again.
10.	Press the A key to replace all modified system files.
11.	Insert any required device driver files requested.
12.	Press the Esc key to have Setup ignore the Windows NT Workstation DRVLIB disk, if you wish.
13.	When the program is complete, reboot your computer.

You can choose the following four main options to repair in the recovery process:

• Inspect Registry Files. By using your ERD, you can repair corrupt portions of the Registry. You can select to repair any or all of the following hives: Default, Security/SAM, Software, and/or System. Changes to the Registry do not require the use of the Windows NT installation CDs.
• Inspect Startup Environment. Any boot files are inspected, dissected, and potentially rejected. Because all default boot files are equivalent, you can use any ERD to replace startup files.
• Verify Windows NT System Files. This option compares any system file (with the system attribute) in the Windows NT directory and any subdirectories and verifies them using the checksum values in the setup.log file. You need your installation disks to perform this repair.
• Inspect Boot Sector. The prime reason that the boot sector becomes invalid is by upgrading MS-DOS, or Windows 95 using the SYS command. Use an ERD (any ERD) and the installation disks to repair this problem.

Each ERD that you create is specific to the type of computer (vendor and CPU type) on which it is created. An ERD that you create on one system does not work on another system. The process of restoring a RISC system containing the Windows NT Workstation as its operating system is similar in concept to the procedure previously described. The individual sequence differs, however, depending on the specific manufacturer for your system.

To restore a RISC-based Windows NT system, complete the following steps:

1.	Start the Windows NT Setup program as your computer’s manual instructs you to.
2.	Insert the ERD, and then follow your computer’s instructions that appear on your monitor.

After the repair is complete, remove the ERD and reboot your system. Creating and maintaining an ERD is one of the most effective troubleshooting tools that you have in your arsenal. It cures a host of ills. It is only effective, however, if you remain diligent in updating it whenever a workstation’s configuration changes.