I encountered this same issue today and I wonder if information was ever discovered.  When I use the html below, and go to the page I always see the folderopen.gif.  Additionally when I *View Source* of the page can find folderopen.gif and folder.gif in the expected source code.

 However when I select and item and do a postback.  I do not see the correct images any more.  I also can't find them when using view source.

 Below is my menu.  Any suggestions are appreciated.

ScrollImageBottom="ig_menuBlueDown.gif" ScrollImageTopDisabled="ig_menuBlueUp_disabled.gif"

ScrollImageTop="ig_menuBlueUp.gif"

ItemPaddingSubMenus="0" ItemPaddingTop="0" ItemSpacingTop="0">

<ItemStyle Font-Size="8pt" Font-Names="Tahoma" ForeColor="#3D4D81" BackColor="Transparent"></ItemStyle>

<Styles>

<ignav:Style Cursor="Default" BorderWidth="1px" BorderColor="Transparent" BackColor="#C1D2EE"

CssClass="TopHover6"></ignav:Style>

<ignav:Style BorderWidth="1px" BorderColor="FloralWhite" ForeColor="Transparent" BackColor="FloralWhite"

CssClass="TopClass6"></ignav:Style>

</Styles>

<DisabledStyle ForeColor="LightGray"></DisabledStyle>

<HoverItemStyle Cursor="Hand" BorderWidth="1px" BackColor="LightSteelBlue">

<BorderDetails ColorTop="204, 204, 204" ColorBottom="204, 204, 204"></BorderDetails>

</HoverItemStyle>

<IslandStyle Cursor="Default" Font-Size="8pt" Font-Names="Tahoma" ForeColor="#3D4D81"

BackColor="Transparent"></IslandStyle>

<ExpandEffects ShadowColor="Gray" Type="Fade" ShadowWidth="0"></ExpandEffects>

<TopSelectedStyle Cursor="Hand" BorderWidth="1px" BorderStyle="Solid" ForeColor="Black" BackColor="FloralWhite"></TopSelectedStyle>

<SeparatorStyle BackgroundImage="ig_menuSep.gif" CustomRules="background-repeat:repeat-x; "></SeparatorStyle>

<Levels>

<ignav:Level Index="0"></ignav:Level>

<ignav:Level Index="1"></ignav:Level>

<ignav:Level Index="2"></ignav:Level>

</Levels>

<Items>

<ignav:Item HoverImageUrl="folder.gif"

Text="Export">

<Style Width="44px" Height="58px">

</Style>

</ignav:Item>

<ignav:Item HoverImageUrl="folder.gif"

ImageUrl="folderopen.gif" HoverClass=""

Text="Hitlists">

<Style Width="44px" Height="58px">

</Style>

</ignav:Item>

<ignav:Item HoverImageUrl="folder.gif"

ImageUrl="folderopen.gif" HoverClass=""

Text="Queries">

<Style Width="44px" Height="58px">

</Style>

</ignav:ultrawebmenu>