Thanks, Boggin. I was able to use the newest version of the Windows Repair Tool, but only after quickly starting the program a second time while the registry scan was still in progress. After that, the repair portion of the program ran successfully, but I still got an error message about the failed registry scan. I'm not sure, but I think this could be due to another error message that I receive at startup about a missing program (.NET Framework 4.0.30319) and the need to reinstall it on the computer. That program might have been removed by a disk cleanup program that I recently used. I tried to reinstall the NET Framework program from the Microsoft website, and that attempt initially appeared to have been successful. Nevertheless, the error message about .NET Framework 4.0.30319 still appears when the computer is restarted, and since Windows XP is no longer supported by Microsoft, it's possible that the .NET Framework reinstallation program can't work properly with my operating system. I think it's perhaps that missing program that is the real problem, and if there's a way to reinstall it, I'd appreciate knowing about it. Many thanks.