I use Firefox for browsing, but I have not checked whether or not it's set to delete cookies on closing; I'll check that out tomorrow.
I had to delete Norton because it was preventing me from upgrading my Btinternet software. However, even after deleting it, I never did get the software to update, hence my use of Firefox. When I tried to re-install Norton, the original CD refused to work, so I downloaded Spyware Doctor. It was only after it was updated recently that I started to get these problems. However, I've now set the options on Outpost to allow 350z uk, and so far no problems today. If necessary, I'll do the same with other favourite sites and that should keep things safe.
Thanks for the help and advice.