I'm wondering how ccleaner is cleaning up my index.dat on my windows vista pc. I thought it just adds entries (nul=...) to the wininit.ini, but i can't find any. everytime i'm cleaning my index.dat i get an alert from my firewall. what does ccleaner do exactly when i mark my index.dat's for cleanup?
It deletes them on reboot, and a reboot is required for them to be removed. Note that as soon as Windows starts it will by itself automatically re-create the index.dat files, however they'll be empty.
In WinXP CCleaner writes the delete operating into the registry here: