Reader Carl Snyder writes: I am told that when we search the web, a history is kept deep in the bowels of our PC. Yet I empty my temp folder and cache regularly. By doing this, am I not getting rid of my history, or is there still a trace? I hate spyware and adware and I swear these gremlins are in my PC, because my PC gets real slow at times. Thanks for your hard work!

The short answer is that if you upgrade to the latest version of either major web browser (IE7 or Firefox 2), you regularly delete your browsing history or private data, and you regularly run anti-spyware and antivirus tools, you're safe.

What you've probably heard relates to older web browsers, namely IE6's use of a file called "index.dat." While you could delete your browsing history, cookies, and temporary internet files in IE6, even after doing so, the browser would leave behind traces of your browsing history in the form of a hidden file called index.dat. This file is notoriously difficult to track down and delete. And, yes, Firefox 1.x used files (cache files) to keep track of where you went, though these were much easier to delete than with IE. There wasn't anything malicious about all of this, it was just an easier way for your browser to figure out where you were going when you typed in a URL.

The good news is that with IE7, index.dat files were discarded, so you can now clear your private information and comfortably know that it has indeed been deleted. In Firefox, click Tools > Clear Private Data to do this. In IE7, click Tools > Delete Browsing History.

If you ever had IE6 (or earlier) or an older version of Firefox on you PC, then you need to delete any index.dat files that might be lingering on your computer. I tried out Index Dat Spy, which lets you locate any of these lingering index.dat files and then choose to delete them as you see fit. (Many index.dat files will turn out to be empty.) It's the only free software I've found that lets you delete these files. (There are many paid alternatives available, too.)

Bear in mind that your browsing history and temporary internet files are not the cause of spyware and adware but are simply records of where you've been on the internet. A privacy risk? Yes. A computer security issue? Not really.

To ensure your computer is spyware free, please refer to this post instead!