Why can't I edit my Main Menu in Ubuntu 10.04 anymore?

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http://askubuntu.com – When I go to the Main Menu icon, right click and choose Edit Menus, nothing happens. Same thing when I go to System - > Preferences -> Main Menu. I found this post and tried out the solution of entering $ alacarte into a Terminal and I got this error: Traceback (most recent call last): File "/usr/bin/alacarte", line 22, in <module> from Alacarte.MainWindow import MainWindow ImportError: No module named Alacarte.MainWindow Not sure what is wrong here but my 10.04 has become rather broken lately. Here are some recent questions of mine that document this: Update Manager updati (HowTos)