Strangest IE9 bug ever (turn off internet, screw up page rendering)

I've got a local webserver (apache) running on my laptop and it is serving up a content management system successfully. Everything looks okay in both IE9 and Firefox.

Today I tried to demo it to someone and the elements were completely misaligned, looked terible in IE9. Still looked okay in Firefox. Tried to figure out what was wrong, even restored an earlier known good build and still messed up. There was no wireless connection at that site and no wired connection either.

I'm back at my place now to diagnose the issue, and there is no issue! By process of elimination, I deduced the ONLY difference between then and now is that now I am on the internet. Bear in mind, I am NOT retrieving anything from the internet for this site. (Not that I am aware.)

I switched off my wireless connection and immediatly my pages started rendering in screwed up fashion again. These pages have tons of framework generated divs and CSS classes so it is not clear where the breakdown开发者_JAVA百科 occurs... but here is my fundamental question:

What could IE9 be doing that simply shutting off my internet connection would cause it to stop rendering a locally served page properly?

Use a network analysis tool like Wireshark to capture the packets that Internet Explorer send (or tries to send) out. You probably will find something there.

There are two things I can think of:

1. You are retrieving some parts from the internet, even though you are not aware of it. Maybe some JavaScript code loads something, or you have url() values in your CSS.
2. It might have something to do with the compatibility view of the IE.

You could try to use a network sniffer to find out, what the request is.

instead of going all the way to WireShark why don't you try the built-in developer tools? Press F12, select the Network tab and start capturing traffic right from IE9. It will show you everything it requests for.