|Does it give you the opportunity to cancel the installation? If it does skip to Step 2.|
Step 1 - Start >> In the Start Search field box type: msconfig <enter>
When the configuration menu opens click on the startup (tab). Look thorugh the list of startup items and find the nortons/symantec installer and disable it. Click Apply and OK .. will be prompted to reboot your computer. Do so.
Step 2 - Now download/run the Nortons Removal Tool:
Reboot your computer and now try the Norton Installation.