My FogBugz installation is functioning correctly, but images aren't showing up.
If I hit the URL of a specific image (e.g., http://localhost/FogBugz/images/add.png), the browser is just returning the URL string instead of the image. If I type the URL of an image that I know doesn't exist, I get a 404 error as expected.
Note: I'm running FogBugz on a Win7 development machine running IIS 7.5.
IIS doesn't come installed by default on Win7. It turns out that when I installed IIS 7.5 I didn't install the Static Content feature.
I went to Control Panel -> Programs -> Turn Windows Features on or off. Under Internet Information Services -> World Wide Web Services -> Common HTTP Features, I checked the box next to Static Content. Images are now loading properly!