I see you are using:
ul#cssmw0 ul.level-1 > li > span > a {menu.css (line 74)
background-color:#333333;
background-image:url(../cssmw0_images/arrow.gif);
background-position:95% 50%;
background-repeat:no-repeat;
border-bottom:1px dotted #9EA3AA;
color:#FFFFFF;
display:block;
font-family:Verdana,Arial,Helvetica,sans-serif;
font-size:12px;
font-style:normal;
font-weight:bold;
height:20px;
line-height:20px;
margin:0;
padding:5px 10px 5px 5px;
text-decoration:none;
width:105%;
try using a pixel width like 205px; instead of a percent width.