Ccleaner misses some files like index.dat when IE9 is used in privacy mode.
example: C:\Users\user\AppData\Roaming\Microsoft\Windows\PrivacIE\Low\index.dat
and also some IE recovery dat files too. (win 7 home premium)
Great find. I have mostly used Firefox, & occasionally Internet Explorer.
I never thought to try to see if CCleaner cleans files in the privacy mode.
Excellent detective work.
Now this, if it does exist, truly needs fixing! Hopefully, they will check into it soon.
do you say it misses it because the file remains after cleaning, or do you feel the dat is not being vacuumed? Which is what occurs with most of the dat files. They are now emptied instead of removed, some times you'll even catch the files being emptied (it's the same boxes that appear when you clear history & cache from within internet explorer).