This is the second time in a space of few days that its happened now, sort it out Mick and find the culprit(s).
Update your Java from the official site and see if it goes away http://java.com/en/download/ Google have updated their fricken Javascript files and it doesn't seem to be compatible with some old versions - it was annoying me all day in work using Chrome and went away as soon as I updated my Java and restarted the browser. If that doesn't work send me a screen shot of your browser and the message.