A horizontal menu with items consisting of an image (with .img-responsive) and text seem to break the row in IE8. I think it has to do with max-width issue in IE8, because if I remove that from img-responsive, it looks good again.
Fiddle: http://jsfiddle.net/DgxxX/
Resize window so you get the horizontal navbar. jsfiddle doesnt seem to work in IE8 so try the code elsewhere I guess.