http://www.talkgraphics.com/images/smilies/wink.gif Automatic is the same setting I'm using, and I have a less generous cache. Could you do this experiment using my website. After you bring up the first page on my site http://members.rogers.com/kdhersey. Mouseover all of the menu items in my menu bar. Two of them have dropdowns, please mouse over those as well, then pick another page and see if my menus have the same problem you experienced.

I have one page with 16 thumbnails and one large picture that load when it opens. I deliberately didn't preload the other images because the entire page would load so slowly on a 56k modem that no-one would wait.