I have just installed IE9 beta and on a specific site I created (HTML5) IE9 jumps to compatibility mode unless I manually tell it not to. I have tried removing several parts of the website but no change. Including removing all CSS includes. On some other website of me it goes just fine.
Also, don’t set it manually because then IE9 remembers the user setting and you can’t turn it back to automatic (or at least I haven’t found how, not even via private browsing and emptying cache)
Anyway. The site where it jumps to compatibility mode: http://alliancesatwar.com/guide/
One where it renders correct: http://geuze.name/basement/ (I can’t post more than 1 hyperlink)
Both use the same doctype and all. Those sites have a lot in common(apart from appearance) using the same basic template(encoding, meta tags, doctype and the same javascript)
It would be great if someone has an answer for me! An HTML5 website that renders in IE7-mode is pretty… lame.