Google Chrome cookies

I have a free version of CCleaner.

On the Applications tab...the section on Google Chrome..."cookies" is checked which means they should be deleted after I click on "RUN CLEANER." But when I log back into google chrome after I run CCleaner, I find some cookies, specifically the user names on some websites, have NOT been deleted. I can manually delete them by running "CLEAR BROWSING DATA" through Chrome's tools, however my question is: WHY AREN'T THESE COOKIES DELETED ON CHROME AFTER I RUN CCLEANER?

does this help; http://forum.piriform.com/index.php?showtopic=40285&p=244877