Please do the following. If any step looks different than how I describe or you have a question please stop and ask. Thank you.
Restore Registry Hives
1. At this point you should be at a command-prompt that will likely be X:\windows\system32>
2. Assuming the C: drive is your main windows drive (if you are not sure you can verify using notepad like you did previously), type c: and hit enter on the keyboard. That is the letter C and a colon.
3. You will now be at the C:\> prompt.
4. Type cd windows\erdnt\hiv-backup and hit enter on the keyboard. That is the letters cd followed by a space and then windows\erdnt\hiv-backup.
5. You should now be at c:\Windows\erdnt\Hiv-backup>
6. Type copy system c:\windows\system32\config\system and hit enter on the keyboard. You should get a message asking if you wish to overwrite. Type Yes and hit enter on the keyboard. It should say 1 file copied.
7. Type copy software c:\windows\system32\config\software and hit enter on the keyboard. Answer Yes to the overwrite message and hit enter. It should say 1 file copied.
8. Type exit and hit enter on the keyboard. Remove the USB drive and click the Restart button.
Let me know if your computer boots up.