This post is more than 2 years old.
I was working on a site recently where I had to work on a CSS page. For some reason, my changes to the CSS were not being reflected in my browser. Of course I had set up my browser to fetch the page for every request, I had even cleared my cache, but I could not for the life of me get the page to reflect the new CSS. I had not had this issue with other file types, so I was a bit loss. On a whim, I went into the IIS Admin, and found the "Enable Content Expiration" field under the HTTP Headers tab. I set it to Expire Immidiately and suddenly things starting working. I'm assuming this is something you would not change on a production system.