Have You Tried Reinstalling It?
First, make sure that "Hidden Files and Folders" and "Protected Operating System Files" are being shown by UNCHECKING the boxes in Windows Explorer/Tools/Folder Options/View tab.
Windows XP- You can usually make system restore run with these steps:
1. Click Start->Run->Type "C:\windows\inf" (without the quotes)
2. Look for a file named: "SR.INF" and RIGHT click on it
3. Choose "Install".
4. In the Files Needed dialog box, click Browse. Locate the Sr.sys file in the i386 folder of the Windows XP CD, (or a good option for those without a Windows XP CD would be to browse the computer itself in the “C\i386” folder) click the “Sr.sys” file, and then click OK.
Follow the prompts, Reboot and System Restore should be ready to use.
Hope this helps.