Images won’t refresh in IE5.0 & 2000Pro

I can’t get images to refresh in Internet Explorer 5.0 when using Windows 2000 professional. Once a picture is downloaded it remains in memory until the computer cycles to a new day. It doesn’t seem to matter if I shut down.. hit the refresh icon..delete history and temp files.. the picture remains. This is a real problem when doing web design because the brower doesn’t update with the new images. Does anyone have any suggestions?