Icon categories disappear in Menu Editor

[Reuben D. Budiardja]

Hello,
If I open menu editor, and click on the icon for an item, usually it shows up 
with a "Select Icon" dialog, and option for "System icons" and "Other icons". 
On the "System icons" line, there's usually drop-down categories such as: 
Application, Action, etc.

For some reason, this afternoon when I try to edit the menu, the drop-down 
category does not show anything, i.e. the drop down is still there but there 
is no options for the categories.

If I right click on the Kick Off itself, then click "Application Launcher 
Settings" and click on Icon, the categories for System Icon is still there.

How do I fix the missing categories ?

Thanks.
RDB