URL Case

I have a site that I have been developing on a hosted IIS platform and I decided to bring up a copy on a local machine to test some changes. I installed IIS Express and have the site running on that. Everything seems to be working as expected apart from a couple of pages. The permalinks for both pages (and all of the other pages that do work for that matter) are of the format http://host/page where page is in lowercase. When I visit the links for the two failing pages I get a 404 page not found error. I have found that if I manually go up into the address bar and change the URL to http://host/Page (capital 1st letter here) then the page loads. All of the other pages load regardless of whether the first letter of the page permalink is upper or lower case. Can anyone explain why this would be playing up for these two pages (I can’t see anything unique about them)?

Thanks

Alan