IE caching problems (and I can't duplicate elsewhere)

I have two drupal installations that I'm working with for experimentation purposes:

antisoc.net (drupal 4.7.0-beta3)
and
pgdev (drupal 4.6.0)

At work, I have some wierd behavior with Internet Explorer -- and I can only assume it's a cache problem. The hard part is I havn't been able to duplicate on other machines. So I can't pinpoint if it's a problem with my installation of drupal(s) or with our settings at work. I'm hoping someone can help me troubleshoot or at least point me in the right direction.

Here's the behavioral problem:
I log into the site as any registered user. Then if I hit the title to go to the home page, I again see the login prompt as if I am not logged in. If I hit the browser's reload button, it recognizes that I'm logged in. There are a couple of other places where I need to do this as well, like in the admin panels. In some cases, it doesn't even save preferences and I have to load up another browser like firefox or wait 'til I get home.

I have IE set to compare cache with the online content every page load. Only my drupal pages give me this problem, and I have several websites running off of the same server (scenespot.org, befunk.com, antisoc.net are all the same server on the same installation of apache). This is also only a problem in IE. I don't have any problems with Opera or Firefox on this or any other system.

I remember having similar problems with other CMS engines (like Xoops), and there was some sort of IE fix that I had to add into my theme to force IE to ignore/clear cache. Unfortunately, I havn't the foggiest idea what that fix was, and I can't figure out where to find it. Perhaps it's not even related to the problem I'm having.

Can anyone help me pinpoint the problem?