cache and IE problem

I have a problem with cache in Internet Exloper.

My website runs on Apache server. If I use Firefox or Opera the files
are cached and don't get images and css sheets from server everytime I
refresh the page.

Bu when it comes to IE it doesn't work. IE doesn't cache this
particular site, but other sites running on other Apache servers are
cached correctly. So I think it isn't related to browser settings, but
with communication between IE and Apache.

I've tried send various headers but with no success

Do you have any idea what may cause that problem?

thanks