Webrick & Internet Explorer... timeout POST issues?

I am using IE 7 beta2… but I have tested this with previous IE
versions (6+) and get the same results… both FireFox and Opera work
fine.

My app does a search (POST), then I click on a record (GET), but if I
hit the BACK button my app breaks because IE tells me that the web page
has expired. I can click on RELOAD, it will ask me to send the POST
request again, I do, and everything is okay… until I navigate through
my site again.

Is this a conflict with Webrick and IE? Is IE timing itself out somehow,
is Webrick timing out IE or are FireFox and Opera just pushing cached
pages back to me instead of trying to reclaim the session? I’ve looked
around for answers, but can’t come up with anything. At first I thought
it was just a general timeout issue but then why do FireFox and Opera
work okay? (other than the obvious reason that IE is junk) Any help
would be great.

I have already tried changing IE’s caching method, no effect. Unchecked
‘Do not save encrypted pages to disk’ (even though my page is no
encrypted… IE told me to do it) So far no luck