Empty Xfce (4.1.90) Menu on panel

[George Garvey]

   I installed 4.1.90 on Gentoo on my system to check it out. Then I
installed it on another user's system to see their response. I put
Xfce Menu on the panel so they would be more comfortable with finding
it where they expected it. But their's is empty (It display a very
little grey box that looks like it may be about 5 pixels by 2). Mine
is not, and displays the menu.
   The desktop menu is available, so they're able to use the system.
   Where could I start looking to figure out what I did wrong on their
system?
   Also, in .xession-errors, they have a message that I don't have:

(xfce4-panel:10417): Gdk-CRITICAL **: file gdkdraw.c: line 412 (gdk_draw_rectangle): assertion `GDK_IS_GC (gc)' failed