With Internet Explorer 8, Microsoft is laboring to balance its commitment to not breaking the web, namely to perpetuate compatibility with content that was designed specifically for IE7 and IE6, but also to embrace modern web standards to reach a level of support that will place IE on par with rival browsers such as Firefox and Opera.
IE8 doesn't really break your website. What happens is, you're sending back content that is not very standards compliant. It worked in IE7 and IE7 wasn't the most standards compliant browser out there. So, for IE8 you just need to go and either use the IE7 rendering engine or go tweak the HTML in your page and make it work, Pete LePage revealed.