You''ve overloaded your cache (files are being held for too many days with too little cache space allocated). Whenever IE downloads an image it finds no space to cache it, so it ends up dropping the compressed file and only keeping the decompressed BMP in memory. To solve this go into internet options and under temporary internet files click delete files to clear the cache. If you continue without clearing the cache you may get to the point where you can''t even view the source for some pages because there is not enough room to store the raw HTML file.