CCleaner is not deleting the index.dat files for Internet Explorer 8. I am using the latest version of CCleaner and have the index.dat item checked in the clean options but they are still there. Is this a Ccleaner bug or just something that happens because IE8 is in beta?

index.dat files for both IE7 and IE8 are special Windows files and are locked for its use.

You will notice after a CCleaner Run that they are marked for deletion after a reboot:
Marked for deletion: C:\Users\{User ID}\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\index.dat

After a reboot Windows re-creates them so it appears that they have not been removed but they will be compressed.

I've been running IE8 on WinXPProSP3 with CCleaner. With administrative rights, the index.dat file gets cleaned properly on the reboot. But for users without administrative rights, that's not the case. Those users can't clear out their cache index. The files themselves are cleared but not the index.

You can see this in action when you use Nirsoft's IECacheView utility. Run an IE8 session as a user without administrative rights then close the browser. Open IECacheView and you'll see the contents of the cache for the logged on user. There's a column on there called Missing File the files will all say No.

Then run your CCleaner to wipe those files. It will also suggest that the index.dat will be scheduled for deletion but that doesn't happen unless you have admin rights. Anyway, after CC runs, go back and refresh IECacheView and you'll see in the Missing File column, the files say Yes indicating the cached files are gone but the listing is there because it looks at the index.dat file. Now reboot, log on as the same non-admin user and check the status of the cache with IECacheView. The index file listing is still there.

If you follow these steps for a user with administrative rights, after you reboot and log on as admin and check the cache with IECacheView, the cache will be clear.

So how to clear the cache of users without admin rights? Log on as an admin and use 7-Zip to navigate to the user's Temporary Internet File folder and clean it out. I recommend this rather than Windows Explorer because 7-Zip can find the folder even when the Explorer Files option is set to hide system files. Otherwise, to use Explorer, you'd have to turn off the hide, delete the folder in question and turn on the hide (for safety).

I'd like to be wrong about cleaning out those IE index.dat files but I've done some extensive testing and I believe this problem is documented in the CCleaner help as a known limitation.

There is another issue with IE8 that has not been addressed and that is the new content in two new file folders: C:\Documents and Settings\USER\IECompatCache and C:\Documents and Settings\USER\IETldCache. I don't know if these are getting cleaned or not.

Three 'index.dat' files not being cleaned in IE 8.

After running CCleaner, and doing a reboot, whilst most index.dat files are being cleaned, I find the following three files are not being cleaned.

Documents and Settings\User\PrivacIE\index.dat
Documents and Settings\User\IETldCache\index.dat
Windows\system32\config\systemprofile\IETldCache\index.dat

(A program that reads the contents of index.dat files was used to confirm that there was content in these files.)

I do hope that this problem with CCleaner can be resolved sooner rather than later.