There is a major security update for Flash Player that you need to install if you haven't done so already. Flash Player is vulnerable to a nasty Clickjacking issue that is affecting all browsers. Adobe is categorizing the vulnerability as critical and advising all users to update promptly.
Read more about the warning and download the updated version of Flash by visiting the Flash Player update bulletin page.
In order to reduce your vulnerability to Clickjacking, it is currently recommended that you promptly apply security updates to vulnerable software and use Firefox with the NoScript extension to browse the internet.
If you do not want to use another browser, here are ways to mitigate your Clickjacking risk with other browsers.
If you have Firefox, Safari or Opera installed in addition to Internet Explorer, you need to also download the flash player with that particular browser to be fully protected). You can uncheck the Google Toolbar so that it does not get installed (it's not needed for Flash to function).