Handi-cap Icon/Virus Warning!

Alright, I haven't downloaded anything or installed anything that I'm aware of, also, I use Mozilla. Yet, I have recently developed an icon in my taskbar that changes from a green handi-cap symbol to the red, "no" symbol (the circle with a line through it). I have Norton 2006, fully updated which I've run several time, and I've alse run some 'spyware removers' I've most likely performed 20 or so scans of these on my system, using the most in-depth options possible, but alas, to no avail. I did have something for Spyware Quake pop-up in my Norton warning window, but I thought I ridded myself of that because it quit. But now, I have this task-bar thing that occasionally pops up a message saying "Your Computer is infected! Critical system error! System detected virus activities. They may cause critical system failure. Please, use antimal software to clean and protect your system from parasite programs. Click here to get available software."

I cannot right-click it and like I said, nothing will rid me of this. Please, some help would be greatly appreciated.