My website has been displaying incorrectly on IE11 due to a media query being executed for widths less than 767px, even though the window width is actually more than that. Interestingly, this issue only occurs randomly and never when the debug window is open.
Currently, I am using Twitter Bootstrap v2.3.1.
Here is an example of one of the problematic CSS rules being executed:
@media all and (max-width:767px)
[class*='span'], [class*='span'].uneditable-input, .row-fluid [class*='span'] {
display: block;
float: none;
width: 100%;
margin-left: 0px;
-webkit-box-sizing: border-box;
-moz-box-sizing: border-box;
box-sizing: border-box;
}