The index.dat file was introduced with Internet Explorer version 4. It is a file that contains a record of every URL you visit when using your browser, and it is incredibly difficult to delete. To the best of my ability, I have found no use for this file, and I'm a little irritated that Microsoft deems it necessary to store my browsing habits in files that they don't tell me about.
I first came across this file after upgrading to Windows ME. I was running Norton SpeedDisk and noticed several blocks of data colored red, meaning that some files contained in that cluster were unmoveable. This set off little warning bells (there had been no such red blocks reported when I was using 98, and SpeedDisk will defrag even the Windows swap file) so I did a little hunting, and came across a tedious but effective method for eliminating all traces of this file. Be warned however, that the file will be re-created, so you'll need to do this on a regular basis.
Windows 95 and Windows 98 users have it a bit easier than Windows ME users (I'm not even going to attempt to explain NT or 2k if someone else wants to do that, feel free).
For Windows 9x users, perform the following steps:
Reboot your computer into MS-DOS mode.
deltree tempor~1 (This will delete all your temporary internet files stored in the "Temporary Internet Files" directory (cached web pages) in addition to the copy of index.dat stored here)
deltree cookies (This will erase all your cookies, so, for example, you'll have to re-check the "Remember Me! box when you log on to E2 the next time you visit the site).
deltree history (This will erase not only the history files you know about, but the copy of index.dat stored here).
Reboot back into Windows. The directories you deleted will be re-created, and the index.dat file(s) will once again begin to spy on you.
For Windows ME users, perform the following steps:
Make a Windows ME Startup Disk. You'll need one blank floppy disk.
Place the disk into your drive and re-boot your computer.
When given the choice, choose the minimal boot option.
Now perform all of the deltree commands given above.
While you're at it, you might also want to deltree c:\_restore ... this directory contains information for Windows ME's "system restore" feature, and I find it accumulates junk to the tune of about half a gig even when I turn off the system restore feature.
Remove the floppy and reboot your computer back into Windows.
The directories you deleted will be re-created, and the index.dat file(s) will once again begin to spy on you.
Up until I discovered this file, I thought Bill Gates was just a capitalist. Anyone got a spare copy of BSD laying around??
Blah blah blah blah not responsible blah blah blah destroyed data blah blah blah at your own risk blah blah blah blah blah lawsuit blah blah blah blah blahdippitydodahBLAH!