Today at work I saw the third (or fourth?) strangest and nastiest bug of my life.
If you send HTML to IE 8.0 via XMLHttpRequest, and that HTML contains a <script> tag on the very first line, the contents of the tag arrive in the browser as several garbage characters (empty squares) when read through the DOM. Fiddler shows that the server is sending everything correctly, and everything is fine in Firefox too.
But if you put at least an " " before the <script> tag, everything works properly. Perhaps it has something to do with all the ASP.NET MVC Ajax support machinery on the client side, but everything works in Firefox.
A horrible bug, even worse than yesterday’s, when it turned out that DataContractSerializer requires tags to be in alphabetical order when they are deserialized into class properties.