Not many people realize there is a component to Windows XP called the Prefetcher. Even fewer desktop/system support people realize the significance of it. This prefetcher for Windows keeps a cache of a lot of programs downloaded by Windows, and acts independently of IE. So if you clear your cache in IE, your downloaded files might still be found in the prefetcher. Most people are tipped off to this location only after a piece of malware has been downloaded (automatically or by accident) and a copy was saved in the prefetch area of Windows, generating an AV alert pointing to this location. This short link is a start to managing the prefetcher cache.