Internet Explorer 7 freezing when W3C valid CSS is added

My Ruby on Rails app is using LivePipe Modals. ( http://livepipe.net/ ) Everything has been fine until I added a "width: 800px;" property my CSS file. Now, IE7 freezes solid whenever I open a Modal.

I have a div with the squeeze class wrapping th开发者_Go百科e content of my page.

div.squeeze {
    width: 800px;
    margin: auto;
}

If I take out the "width: 800px;" everything works on IE7 again. All of the HTML and CSS are valid according to the W3C validators.

Has anyone seen this before? Any thoughts on a workaround? I'd really appreciate any help.

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Yeah, @Pekka: I'd seen something like this before, it actually crashes the browser.

Is there also a float involved somewhere with that div? I know IE drove me in circles for a few days over something similar. There was an interaction between a float and a width that it just didn't like. After a lot of searching on the net I finally found similar complaints but no one with a clear idea why it was true (pretty much hands-in-the-air "well, that's IE for ya" resignation).

My best suggestion (if I'm right in the div also floating from a previous declaration) is to find a way to do it without the float. I searched "ie crash width float" on Google for pointers...this page suggested it was positioning rather than a float, for example.