Hi,
This was caused by a new feature where people had asked to be able to use menu icons in Artisteer skins.
You can solve this in several ways. I added this to the Artisteer skins that ship with mojoPortal to hide them by default
.art-menu .t img { display:none;}
.art-vmenu .t img { display:none; }
but this only affects the copy of the skins in /Data/skins, the ones you have in the site specific skin folders are not touched during upgrade so you may need to add it yourself.
The problem is that in the artisteer skins it does not show you the icons in the page settings page because the CSS has this in stylemojo.css:
.logolist,.pageicons,.skiplink { display:none; }
you can remove the ".pageicons," and then you will see them in page settings and you can set the icon for home page to blank.gif or None
or you can change temporarily to the mitchinson-earthy skin and then go to page settings for the home page and set the icon to blank.gif or None
Hope it helps,
Joe