Laptop takes 25 minutes after black screen, to start-up

A week ago, my laptop would not start properly: it froze after the Toshiba logo, and took 1hour to boot. It now takes about 30 minutes before it loads, and the browsers are so slow, with things sometimes moving in slow motion. There is no virus, but it appears Norton is blocking the laptop to a certain degree. I got a mesage from NIS asking me to copy my product number, and the Norton Removal Tool download appeared. I was asked to remove and re-install Norton.

My Norton came pre-installed with the laptop (I bought them as a bundle), and so I do not know have the product key. Also, I did not fully understand how togo about the removal and re-installation. Please kindly assist me, as I attend internet college and need this fixed. Also, will this fix my laptop?

Thank you.

Divoire