Hi, sorry I can't remember the exact details but Norton is a sod to completely get rid of. Seem to remember it was quite a laborious process and had to Google for help. When you install it they leave something behind that means you get these pop ups etc. I'm sure some of the more techy guys on here will be able to help.
I agree with getting maladaware installed. I used to have loads of problems with messages saying you have accessed so and so and this is the police pay so much to get your computer working. This was a scam and with maladaware this no longer happens. Run it alongside Mcafee and have no problems now