Any idea what might be causing the vertical lines on the left and right of this message box?
<div runat = "server" id = "divMsgbox">
<eo:MsgBox ID="MsgBox1" runat="server" AllowResize="True"
CloseButtonUrl="00020440" ControlSkinID="None" HeaderHtml="Dialog Title"
HeaderHtmlFormat='<div style="padding-top:4px">{0}</div>'
HeaderImageHeight="27" HeaderImageUrl="00020441" Height="216px" MinHeight="100"
MinWidth="150" Width="320px" BorderStyle="Inset"
BackShadeColor="ActiveBorder">
<HeaderStyleActive CssText="background-image:url(00020442);color:#444444;font-family:'trebuchet ms';font-size:10pt;font-weight:bold;padding-bottom:7px;padding-left:8px;padding-right:0px;padding-top:0px;" />
<BorderImages BottomBorder="00020409,00020429" BottomLeftCorner="00020408,00020428" BottomRightCorner="00020410,00020430" LeftBorder="00020406,00020426" RightBorder="00020407,00020427" TopBorder="00020402,00020422" TopLeftCorner="00020401,00020421" TopLeftCornerBottom="00020404,00020424" TopRightCorner="00020403,00020423" TopRightCornerBottom="00020405,00020425" />
<FooterStyleActive CssText="background-color:#f0f0f0; padding-right: 4px; padding-left: 4px; padding-bottom: 4px; padding-top: 4px; font-family: tahoma; font-size: 8pt; " />
<ContentStyleActive CssText="background-color:#f0f0f0; padding-right: 4px; padding-left: 4px; padding-bottom: 4px; padding-top: 4px; font-family: tahoma; font-size: 8pt; " />
</eo:MsgBox>
</div>