Index: wp-admin/css/wp-admin.dev.css
===================================================================
--- wp-admin/css/wp-admin.dev.css	(revision 20336)
+++ wp-admin/css/wp-admin.dev.css	(working copy)
@@ -1506,6 +1506,10 @@
 	z-index: 1001;
 }
 
+html.ie8 #adminmenu li.menu-top:hover .wp-menu-arrow {
+	display: none;
+}
+
 #adminmenu .wp-menu-arrow div {
 	position: absolute;
 	top: 7px;