IE9 renders differently on localhost versus qualified URL

I'm having a weird problem that I wasn't even sure how to search for an answer.

Basically, if I view my site in IE9 using a localhost URL, it renders perfectly.

(example: localhost/site/index.html)

But, if I view that exact same page, still running on localhost using IIS, but with the fully qualified URL, IE9 seems to ignore several CSS selectors, specifically anything that uses CSS3 like rounded corners and box shadows.

(example: d6vhr1m1.mydomain.com/site/index.html)

Is there a known bug/issue here that I'm missing?

Oh, I should also mention, both versions show that they are rendering in Standards Compliant mode (according to the bookmarklet I use to check).

Thank you.
-RED

Here's where I found the solution, in case anyone else has this issue:

Pages in IE render differently when served through the ASP.NET Development server and Production Server - Raj Kaimal

Since the qualified URL is considered to be within my local intranet, IE by default renders the site in 'compatibility mode' so I was seeing the lack of CSS3 features supported.

Disabling this option allows the site to render properly, although this seems like a big issue for people who develop solely for intranets. Our current development site is all technically on an intranet, so the site won't look correctly to stakeholders unless they disable this option too.

Glad you got it sorted and thanks for posting the answer as I am sure it will be helpful to a few people.:)

We were having an issue with compatibility modes too, so I ended up just adding:
<meta http-equiv="X-UA-Compatible" content="IE=Edge">

Since I knew it worked fine in IE7, 8, and 9.