What Is It? A Shield With An Asterik?

It is on the lower right taskbar - when I click on it - it pops up a block that says that an automatic update is ready - it says it has been identified by windows - I of course cannot click on downloading it because I don't know what it is. I run spybot and zone alarm to keep bad stuff eliminated, but this thing just hangs around. I also use Firefox instead of IE. The little shield is yellow with a black asterik. The pop up block is very plain - no ID on it - very suspicious. HELP!