I must say I am amazed at all the workable alternatives to something that was supposed to be performed by CCleaner. That's why I downloaded CCleaner today and donated the $20. The original issue stated was: Well, I had exactly the same problem when trying to do this today. I rebooted after running CCleaner and the index.dat files were still the same size. However, I elected to try running in Safe Mode for my next attempt (I'm using XP sp2) and using CCleaner from there. After reboot, my index.dat files were essentially the size indicated by those on the forum. So, Habari24 obviously my suggestion would be to try using CCleaner from Safe Mode when deleting index.dat is the issue. While I'm fairly versed in using the Command Line Interface [Command (DOS) Prompt] and have no problems with the suggestions offered. I just think Safe Mode is a whole lot easier in this case. At least, it worked for me. I also think CCleaner, though a very nice utility, should perform as advertised without these extra steps. I hope this helps and I hope you get a chance to see this posting which is a quite a bit later than your original posting. p.s. Getting into safe mode is easy -- just boot your system and as soon as it starts just start tapping the F8 function key until the startup menu is offered. Your computer will offer you several startup options. The first of which will be safe mode.