Actually if anyone wants a non-code workaround to this, then here is a clunky solution.
Just create a new Page Type of Menu Link.
Set the Link parameter to External Link and set the url to the web root /
Make this the parent of your other pages
I'm not sure if I understand you, but are you sending people to the homepage when they click on Contact now? You'd better send them to the first child instead, don't you think?
You can also split the menu in a header-type menu call with a link, and the real menu call. Like so (example from a client site:
www.ksi-advies.nl):
// show the parent as non-linked header
show_menu2(1, SM2_ROOT, SM2_MAX, SM2_CRUMB|SM2_CURRTREE,'<h2>[menu_title]</h2>','','','',false,false);
// then show the menu
show_menu2(1,SM2_ROOT+1,SM2_CURR+1,SM2_TRIM|SM2_CURRTREE,'[li]<div class="bg_menu">[a][menu_title]</a></div>','</li>','[ul]','</ul>',false,false);
Clicking on the top menu generates the left menu automatically.
I'm sure you can also do some fancy showmenu2 coding with if-then constructions. See
http://code.jellycan.com/show_menu2/