What is startup repair?
Following is direct from the Win 7 Help system:
Startup Repair is a Windows recovery tool that can fix certain system problems that might prevent Windows from starting. Startup Repair scans your computer for the problem and then tries to fix it so your computer can start correctly.
What is system restore?
Following is direct from the Win 7 help system:
System Restore helps you restore your computer's system files to an earlier point in time. It's a way to undo system changes to your computer without affecting your personal files, such as e‑mail, documents, or photos.
Sometimes, the installation of a program or a
driver can cause an unexpected change to your computer or cause Windows to behave unpredictably. Usually, uninstalling the program or driver corrects the problem. If uninstalling doesn't fix the problem, you can try restoring your computer's system to an earlier date when everything worked correctly.
A startup repair is not going to alter any of your data files.
A system restore is not going to alter any of your data files.
You will find the following tutorials instructive:
Startup Repair
System Restore - How to use
If you boot from a System Repair Disc, and go to a command prompt, then you will be able to rename files/replace files without any permission difficulties.