[houston1]

Index.dat does different things depending on what version of Windows you are using, but it generally stores your user settings, etc. You will never be able to modify/delete it because it is always in use by Windows, you may be able to boot to Dos (hit F8 during startup) and delete it from there, or boot from a floppy and go to the C: drive and try deleting it.

[smythe]

In an earlier version of IE, about 5 years ago, I managed to delete the index.dat, rebooted the machine, opened windows explorer, and then IE, and watched windows put in a new index.dat file. I then changed the properties to read only, and that worked, except that I would receive frequent message to delete the cookie file and reboot. I ignored it for a time, then dicovered that I could delete the content of the index.dat file when I chose to (like just before I register a MS program) and resave it. I now have my index.dat file setting so that when I right click on the file in explorer, it automatically opens in notepad, saving a few steps. I used the idea of deleting the content of the file and resaving it to corrupt the annoying clip-it help file in MS Office 97 and ended a great deal of frustration, as it never helped and I just wanted to kick it.