Firefox, Opera and Chrome display fine.
IE8 does not, and I cannot install IE9 on Windows XP.
I looked at the HTML generated, and IE8 seems to show that "picture not found icon" of size 28x30 whereas Chrome shows a blank image of size 1x1.
HTML (from Chrome):
Properties (from IE):
<img id="menuitem-1073-arrowEl" src="data:image/gif;base64,R0lGODlhAQABAID/AMDAwAAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==" class="">
It seems to set an "arrow" element but blank, as it's not a menu with a sub menu (the above code/screenshot is taken from the "Sort Ascending" element)