Well isn't that odd.. here is the code for that area.. and both are using the same class, so they should look identical

<br /><td class=\"menubar\" valign=\"middle\" width=\"50%\">$menu2</td><td class=\"menubar\" width=\"50%\" align=\"right\" valign=\"middle\">$menu </td></tr>$tbclose<br />";
Since when you are logged in, there are links that are supposed to be displayed set by the $menu2 variable.
But since you are logged out, there is no $menu2 information, somewhere it must be getting a different class.
I'm too tired to look for it, so I'll let it be for now. It is just a cosmetic issue, and the next version of PP is headed to templates anyway
