You work for a large company that uses the Internet to do various jobs and track clients from time to time, and you are sitting there one day busy as a bee. In come the MS rep and the company president asking you to get up so that they can check your computer. Odds are that you have frequented several web locations, maybe checking your stocks, or maybe doing some online banking. You are confident that you cleaned out your history files and dumped any sign of surfing the Internet, right? Wrong! That is, if you are using Microsoft Internet Explorer 3.0X for Windows 95 or Windows NT, Microsoft Internet Explorer 4.0X for Windows 9X and possibly Windows NT, including Microsoft Windows 95 OSR 2.0 and greater, Microsoft Windows 98 and Microsoft Windows NT 4.0 (all SPs). The following also applies to Microsoft Internet Explorer 5.0ß. You watch as the MS person slips a disk in your computer and recalls all of your visited sites. At this point you are just dumbfounded because you are pretty good with the computer and you are wondering how this could have happened. The answer is simple. There are hidden files which record user-activity called index.dat, which don’t go away as easily as some files do. Even though you may think that you removed your history files, you didn’t. When one of the above programs is installed, there will be several hidden files in several directories. These files are called index.dat in IE4. The directory-names depend on the language version of the program that you are using. These files (index.dat) contain URLs and Cookies of websites previously visited by the user. When the user tries to erase all traces of earlier visited web pages by going through the following procedure: Start Inter Explorer, View, Internet Options, Clear History, Yes, Delete Files, Yes, Settings, View Files, Ctrl-A, Del, Yes, the history information remains in (at least) one of the (index.dat) files.