I have PC on XP professional and tried to install NIS 2011 from CD purchased off Amazon. It wanted to uninstall prior Norton security but took forever so I stopped it. It appears to have uninstalled most of my applications. Windows Installer keeps popping up trying to install various applications but errors out "can't find required file". I can't open most of my applications i.e. Microsoft Word, Excel, Adobe products, printer/scanner software and many other applications. When I try to access my internet browser, I have to hit the cancel button several times to cancel the Windows Installer attempts to install various software. I uninstalled Norton but that didn't work either. I downloaded and tried running REGSERVO program to fix registry issues but it didn't help. Now when I try to install NIS 20110from the CD I can't type some of the required letters in the product key. Any idea what I can do to fix this?