Here's an AHK script to delete all index.dat files on the system partition. It should only be run using Windows Registry RunOnce Key. See my RunItOnce for a simple way of setting that up.
Code
; IndexDotDatCleaner to delete all index.dat files on system
; partition. Should only be run via RunOnce key in Registry
; HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce
;
; (See my RunItOnce program for a convenient way to add it.)
;
; It searches the entire partition for index.dat files. It will slow
; down the boot. It should only be used occasionally to clean them all out.
;
; MilesAhead
;
#NoTrayIcon
stringleft,sysdrive,A_WinDir,3
SetWorkingDir,%sysdrive%
Loop,index.dat,,1
{
FileDelete,%A_LoopFileFullPath%
}