IE9不应用链接样式表

I have a wierd problem. I developed a site that works fine in most browsers. I just upgraded to IE9 and none of my styles are being applied. I'm viewing this on my local pc as this site is not on the internet just yet. All in-line or page level styles get applied correctly but the styles linked from external css files in the HEAD section aren't applied at all. If I use the developer toolbar and view the site as IE8, IE7, or any other mode the sites work fine. There's about 6 style sheets and no extra components so it shouldn't be an issue of too many style sheets. I can't figure what is causing this. Anybody else seen this?I have a wierd problem. I developed a site that