Close all your web browsers.

Heck, reboot your machine.

When it comes back up, launch Chrome and then go to the wrench icon in the upper right of the browser (if on PC, not sure on Mac), go to Options, then to Under the Hood, then in the Privacy section choose "Clear Browsing Data" and from the pull down choose "From the Beginning of Time" and check Empty the cache and Delete cookies and other site and plug-in data. Then click "Clear browsing data"