What is a silver octagon with a red & yellow banner or worm across it on my taskbar? How do I get rid of it?

It just appeared one day when I turned my pc on. I did not download anything new. It doesn't do anything when I right or left click on it. No menu pops up to say what it is. I have tried spybot, adware remover and error fixer to get rid of it with no results. I have windows ME. It hasn't stopped me from doing whatever I want on my pc. No one I have asked has ever seen anything like it. Does anyone out there know what it is %26amp; how to get rid of it?|||ctrl+alt+del. then stop every process you dont need. you wont wreck anything. you might turn something off and things dont work. but just restart your computer and try again and dont end that prosses again.