Featured Freeware: Click&Clean
Firefox and Internet Explorer extension Click&Clean is aimed at those who prefer the history-sweeping CCleaner to Firefox's built-in browsing tracks sterilizer. Click&Clean takes the same number of mouse clicks or keyboard strokes to activate as the native cleaner, opening a CCleaner window preconfigured for cleaning Firefox. Obviously, you must download CCleaner for Click&Clean to work.
Click&Clean adds only a single button to your Firefox toolbar, so it won't clutter your browser window. Clicking it opened the CCleaner interface immediately, and from there you can have it wipe your tracks with the automatic configuration, or you can make adjustments to suit your needs. If you're addicted to the digital ammonia of CCleaner and you're a Firefox user, Click&Clean is one surefire way to make your hard drive sparkle.
Seth peers into the deep, dark corners of software so that you don't have to. He has yet to suffer a single nightmare about OS/2. You can follow him on Twitter. 
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You not right,
open Firefox cache
C:\Documents and Settings\usrname\Local Settings\Application Data\Mozilla\Firefox\Profiles\abcd123h.default\Cache (WinXP)
click on Click&Clean button in Firefox and see how it works ( cache is clearing)
If not understand, see step by step instruction in http://www.hotcleaner.com/