Hi rgds,
Your answer prompted me to do a complete search for index.dat files 1) immediately after a restart, 2) after running CCleaner.
I'm logged in as an administrator, all files, including system files are "unhidden". In other words, my search as full access to the computer.
Try it sometime. You will be surprised at how little CCleaner actually does in this area. This is probably for the best since a wrong step here can have serious consequences.
Since I am security conscious, then I do use Tracks Eraser which uses a zero fill approach. This leaves XP Pro happy, since not all index.dat files are automatically replaced/restored upon a reboot. If anyone doubts the accuracy of that statement then just delete all of your index.dat files and be prepared to have some very unusual performance untill you have replaced the missing files with ones from a friend's computer.
I did notice in the list of bug fixes this last time then a problem related to a Vista index.dat file was fixed.
Overall, I rate CCleaner as excellent and the best in his field.
Thanks,
Karl Snooks