This article was previously published under Q264578
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When you boot to the startup disk from Microsoft Windows Millennium Edition and run the command ebdundo.exe, you receive no response and there is no indication that any actions have been performed.
The command ebdundo.exe is designed to work only when a failed system-restore operation was the last action performed on the system.
When System Restore performs a restore operation, the system backs up current registry files; it creates a file by the name of Rstrsig.dat in the folder C:\Windows\System\Restore. This is an eight-byte file whose content is simply "rstrsig." This file allows the command ebdundo.exe to verify on startup that the last operation was a restore operation. When this situation is detected, any selection from the Start menu results in the following message: System Restore detects that a restore operation was the last operation completed.
Revert the Restore changes made to the system.
Do not revert the Restore changes made to the system.
It is recommended that you revert (undo) the changes to your system made by System Restore and restart the computer before you proceed. If you choose not to revert these changes, this option is no longer available.
If you select option 1, your system reverts the changes made by the restore operation. If you select option 2, your system boots to the A: prompt, and the file rstrsig.dat is removed from the system. You are then no longer able to revert the system back to its previous state by using the startup disk.
Ebdundo.exe is not designed to run System Restore from a command-prompt boot. It is a last-resort tool that adds one final safety measure for users who find themselves in a no-boot situation after having performed a restore operation.