I doubt very much that the web server version is a causal factor of the problem. Web servers just serve files, all rendering happens after the files are received in the browser.
More likely something else is causing it like missing files or files that can't be loaded because of permissions, or .ashx extension is not correctly registered on the server.
Do other skins work on IIS 7.5? Are you sure it is just your specific skin that has a problem?
Hope it helps,
Joe