file icons always inaccurate

System

I have caching disabled in both IE and Mozilla. It seems like the first time I go to a directory, some of the icons (pencil/lock/key/etc.) are pretty much always inaccurate until I iwrefresh. The most common thing seems to be the pencil missing - after iwrefresh the pencil appears. This is true even if it's been quite some time since I last browsed the directory. Even when I iwrefresh the icons can still be wrong - it can take multiple iwrefreshes.

Has anyone else noticed this? Is this browser caching, Apache caching or something else?

Is there any way to remove these icons, since the visual clues they give to users are inaccurate?

TeamSite 5.5.2 on Windows.

Actually it's not just the icons - sometimes files that have been added will not appear until iwrefresh.