Regular primary-links styling is broken

When I use the regular primary-links, each menu item is displayed on its own line. It's as if the ul/li is styled as "display: block;": instead of 'inline'

Also I notice there seems to be an extra level of <ul> enclosing the primary-links:

<ul class="menu">
  <ul class="menu">
    <li>.....
    <li>
   </ul>
</ul>

But I switch to use suckerfish menu and that has problem.