Norton Security Scan not installing

Hi,

I recently installed NSS on my PC, tried it out, uninstalled, and I am now trying to reinstall it so I can copy it to my usb key as a backup solution. However it doesn't want to install anymore. I ran the norton removal tool prior to attempting reinstallation, downloaded the installer, it extracts the install files, downloads the necessary files from the internet and simply stops. No Norton or Symantec folders are created in "Program Files" or the start menu, no entry is created in the "Add/Remove Program" list. Any ideas what could be going wrong?