I havent been able to successfully install a Windows update for a year now. When I search for updates, I get the error code: 800700C1. Also, I have been trying to install updates for my Norton Internet Security, and suprise, I havent been able to do that either. WHen I try to uninstall the Norton program, it says there was a problem authenticating your Microsoft Windows Installer. I have tried EVERYTHING on Norton's website to try and fix that problem, but no such luck. Please help.