http://jsfiddle.net/jgehrs/MgcDU/3103/
I have this block of code, which should lead to 4 equal sizes, all arranged horizontally, but, as you can see, the 4th block is transferred to a new line. I used the bootloader for several days, and this is the first time I have seen this.
<div id='middle' class='row'> <div class='span3'> <div>1</div> </div> <div class='span3'> <div>2</div> </div> <div class='span3'> <div>3</div> </div> <div class='span3'> <div>4</div> </div>

Edit: here is jsFiddle showing the problem.
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