Having successfully installed Caedium on Ubuntu 11.04 it appears that the menu bar (File Edit etc.) is missing.
Edit: This is fixed in Caedium v3.0.2.
Edit: After more investigation I suggest you skip this advice and start at the comment "Move mouse cursor to top of desktop to reveal menu bar".
I'm guessing that you are using the Unity desktop rather than the classic Gnome desktop. One option is to switch to the classic Gnome desktop according to:
"Logout and then after clicking on your username, select Ubuntu Classic Desktop at the bottom of the login screen." Thanks to http://scottlinux.com/2011/03/05/ubuntu-11-04-change-from-unity-to-class...
Otherwise it sounds like you might have the following packages installed:
These packages provide options (Desktop settings) to control where the menu bar appears, I guess by default it hides the menu bar, so adjust accordingly or remove these packages.
It appears that a number of users have had success in recovering their menu bar by removing the package appmenu-gtk. Thanks to http://mamchenkov.net/wordpress/2010/05/18/missing-main-menu-bar-in-gnom...
I removed the appmenu-gtk package and recovered the menu bar.
I was already using Ubuntu Gnome classic.
Ubuntu 11.04 uses the Unity desktop by default. Under this desktop manager the standard menu bar (File, Edit, etc.) is hidden until you move your mouse cursor to the very top of the desktop - then the menu bar is revealed.
If you switch to the classic Gnome desktop manager under Ubuntu 11.04, the Caedium menu bar is likely to disappear. In this case try uninstalling the appmenu-gtk package to fix the problem.