Hi Harold,
It sounds like you need to sort out the desktop problem first. One of the first things many infections will try to do is protect themselves from discovery and removal. Norton's primary mission is to discover and remove that type of infection.
I will assume that you have run the usual scans and found nothing. If that is the case then it might be wise to go to one of the sites listed below and have them help you discover if an infection is the problem.
http://www.bleepingcomputer.com
http://forums.whatthetech.com/
http://www.geekstogo.com/forum/
http://www.cybertechhelp.com/forums/
Keep us posted