When developing most websites they are setup to work with most "major" browsers out there. Recently most web developers have dropped support for IE6, but many sites still require backward functionality for old IE settings especially within corporate websites. And IE8 has a "compatibility mode" setting to accommodate this. Just recently I found out that IE8's compatibility mode has a hidden "gotchya" within its setttings:
First of all you can test how a site appears in various versions of IE by using IE8's built in compatibility mode. To do so just open the site up in IE8 and then press your function 12 (F12) key. This will open up IE8's built-in developer toolbar.
At the right side of the bar's menu are two drop downs with various compatibility settings.
What I didn't know is that IE8 places any intranet site into compatibility mode by default. At work we often stage sites for clients to see before they go live and to give them an immediately accessibly I.P. address we create a subdomain within our company's domain. Internally these sites end up indentified as intranet sites to IE8. They are therefore placed into compatibility mode automatically.
To turn this off do the following:
Click on tools - compatibility view settings in the IE8 Menu
In the window that opens uncheck the "Display intranet sites in compatibility mode" checkbox