Current configuration is Windows Server 2008 R2, IIS 7.5, PHP 5.3.14 for CGI, WordPress 3.4.
My issue is that whenever I upload files in a post, the permissions are not set correctly. On the file that gets uploaded, the permissions show that the IIS_IUSRS group doesn't have sufficient permissions to the file (List Folder / read data permission only). The interesting part is that the other resized thumbnails that are automatically generated by WordPress during the file upload are given the correct Modify permission to the IIS_IUSRS group. This seems to be happening because the main image is inheriting permissions from "Parent Object" whereas the thumbnail images are inheriting permissions from my /uploads directory a few folders up.
Something must have changed with respect to how file uploads are handled in 3.4 perhaps? I was running 3.3 without an issue and the moment I updated to 3.4 I started seeing this.
Without the correct permissions on the main image, WordPress essentially can't read the file and you end up with a broken image that throws a 500 error when you try to access the image's URL.