I agree with tg, Norton is VERY notorious for slowing down PCs. I work as an IT professional in the Seattle, WA area and I see this issue every day.
If you MUST use Norton: How much RAM does your PC have? Can you post a HiJackThis Log? (Guessing your problem away won't work - you need to work with the folks on this forum to obtain your results). I noticed your frustration in the Introductions post.
Have some patience and answer some questions.
Answer the questions from tg1911 (forum moderator) and myself and we will try to help you.