format or erase in CCleaner Discussion Posted January 30, 2008 · Report reply I'm not sure what you actually mean by formatting temp internet files. CC will overwrite these files (if the option is selected) which makes them unrecoverable by any method. One overwrite is sufficient. Formatting, at its most secure, is simply overwriting physical areas of the disk. It was a little tongue in cheek to mention another security method. Temp internet files from an individual's surfing can be overwritten adequately by CC. If you have access to very sensitive data, such as that which seems to be handled so nonchalantly by our leaders, then your PC should be subject to a security procedure which (amongst other things) sees it physically secured at all times, fully password protected, no access by any other person, data encrypted and at the end of its use by you the hard drive removed and physically destroyed. But that isn't what most people will do because they aren't in a position to access such sensitive data. Rgds.