To quote from the hMenu documentation: "Please note that Microsoft itself recommends preloading. As you can see at the Microsoft website, this bug only happens in IE 5.5 or later (it wasn't there in 5.0) and it is not a bug but, instead, it's something done "by design" (this means "intentional", right?) by the IE team. Microsoft will not fix the cache bug; the cache bug does not exist. Instead, you are expected to fix your stuff, and the recommended way is preloading the images. Thank you Microsoft for making things so much easier for you." hMenu provides a function to automatically cache the images from the style sheet in the standard themes - to use it, the following must be added to the bottom of the page, just above the </body> tag: DynarchMenu.preloadImages(new RegExp("^/hmenu/")); It will need to be wrapped in something to ensure it only gets called on MSIE 5.5 or above (all other browsers don't suffer this bug so no need to preload and cache images for them).