You don’t have a code issue, just CSS. In your default.css, just at the end, add this:

#menu-under-header .navbar-inner ul{clear:both !important; width:1000px;}
.menu-header-container{clear:both !important;}
#social-networking{clear:both !important;}

and that’s it. You may want to add a position for social networking. IN that case, replace the last line with this:

#social-networking{clear:both !important; position:relative; left:760px;}

EDIT: SEE THE FOLLOWING THEN:

first of all, it seems like you’re calling you pagenavi twice. And yes, you still have CSS issues, see below to correct:

.wp-pagenavi span.pages{clear:both !important; text-align:left !important; margin:5px !important;}
.wp-pagenavi a.larger, .smaller, .previous, .last, .nextpostslink, .previouspostslink{width:auto !important; padding:20px !important;margin-top:15px;}

so, just check your page template for that additional call to page navi, add the CSS fix and lmk if it works out