Problems with refreshing a webpage

Hi all

I don't think my subject is correct, but I didn't know what else to put. Here's my problem.

Everytime I do a search (on Sharkyforums or any other website), I'll get the search results. However, if I click on the Back button in IE, I don't go back to the main search page.

Instead, I get a "Warning: Page has expired" screen. I need to click on the Back button again to get to the main search page.

At first I thought it was maybe a security issue, so I lowered my IE security settings. That did not work.

It's really not a big deal, more like a nuisance. But I also want to find out why it does that and if I can remedy it.

I'm running WinXP (SP1) and IE6.

Thanks!
Brew