Microsoft-IIS is unreliable

// Blacklist of servers whose content-location headers are unreliable
// and should be ignored. This is a comma-separated list of server
// names, with no spaces before or after the commas. If the server
// name you want to add here contains a comma, use a period instead.
pref("network.http.content-location.bogus-servers", "Microsoft-IIS/4.0, Microsoft-IIS/5.0, Microsoft-IIS/6.0, Oracle9iAS/9.0.2, Oracle9iAS (1.0.2.2.1)");